Disputed Statements

Indigo, Colors

Standing Scholarly debate

Concerns Origin Period End Year

Currently States 1704

According To Newtonian optics: the seven-colour spectrum

Isaac Newton's own account in Opticks (London, 1704) describes how he arrived at seven spectral colours: his earliest prism observations distinguished five bands, and he settled on seven, adding orange and indigo, by explicit analogy with the seven intervals of the musical octave, a numerological choice rather than a further optical finding. Reading Newton's own text against the continuous gradient a prism actually produces shows the seven-fold division is an interpretive choice about where to draw lines in that continuum, not a count nature supplies; observers from Newton's own time onward have disputed whether indigo is visually distinct from blue and violet at all. Any scheme in this atlas that treats seven colours as given inherits Newton's seventeenth-century analogy to the octave rather than an independent observation.

Source Opticks: or, a Treatise of the Reflexions, Refractions, Inflexions and Colours of Light, Isaac Newton tier 1

Indo-European, Language Families

Standing Scholarly debate

Concerns Homeland Hypothesis

Currently States The Pontic-Caspian steppe, on the steppe hypothesis; Anatolia, on the rival account that ties the spread to the coming of farming.

Marija Gimbutas proposed the steppe origin and David Anthony has argued it in detail from the archaeology of the horse and the wheel. Colin Renfrew argued instead for an Anatolian origin carried by agriculture. Ancient DNA published from 2015 onwards has moved the weight of opinion towards the steppe without ending the argument.

Source The Horse, the Wheel, and Language: How Bronze-Age Riders from the Eurasian Steppes Shaped the Modern World, David W. Anthony tier 1

Indra, Deities

Standing Scholarly debate

Concerns Origin of the Name

Currently States Indra's name has no securely established Indo-European etymology.

Sanskritists have proposed multiple derivations, including roots connected to strength and to rain, but none commands general agreement, and some historical linguists argue the name may descend from a substrate language absorbed into early Vedic religion rather than from any Indo-Iranian or Indo-European root at all, a disagreement that has run across more than a century of scholarship with no resolution in sight.

Source Vedic Mythology, Arthur Anthony Macdonell tier 1

Innocent III, Figures

Standing Scholarly debate

Concerns Lifespan or Floruit Start Year

Currently States 1160

The source marks this year circa, its own approximate estimate rather than a fixed date.

Source The Oxford Dictionary of the Christian Church, 3rd revised edition, F. L. Cross and E. A. Livingstone (eds.) tier 1

Innocent III, Figures

Standing Scholarly debate

Concerns Lifespan or Floruit End Year

Currently States 1216

The source marks this year circa, its own approximate estimate rather than a fixed date.

Source The Oxford Dictionary of the Christian Church, 3rd revised edition, F. L. Cross and E. A. Livingstone (eds.) tier 1

Instituto Nacional de Antropologia e Historia (INAH), Custodians & Museums

Standing Scholarly debate

Concerns Relevant Holding

Currently States Maya Codex of Mexico, formerly the Grolier Codex, formally authenticated by INAH in 2018 after decades of dispute

Mexico's Instituto Nacional de Antropologia e Historia holds and, in 2018, formally authenticated the Maya Codex of Mexico, previously known as the Grolier Codex, a pre-Columbian Maya bark-paper manuscript. INAH's own published 2018 technical authentication documents that the codex had been suspected of modern forgery for roughly four decades after its appearance in the 1970s, since its unusual survival history and stylistic departures from other known Maya codices raised doubts among specialists. The method behind the 2018 authentication combined radiocarbon dating of the paper, pigment analysis identifying materials consistent with pre-Columbian manufacture and unavailable to a modern forger, and comparative codicological analysis against the three other securely authenticated Maya codices. Some scholarly skepticism has continued even after INAH's ruling, since institutional authentication of an object already in an institution's own collection carries an inherent question of independence, though no published technical rebuttal of the specific findings has appeared. The relevant holding's authenticity is recorded as debated rather than fully closed.

Source The Maya Codex of Mexico: authentication of the former Grolier Codex (INAH, 2018), Instituto Nacional de Antropologia e Historia tier 1

Instruction of Amenemope, Other Writings

Standing Scholarly debate

Concerns Era of Composition Start Year

Currently States -1300

Egyptologists place the Instruction of Amenemope within the New Kingdom but disagree on the precise window: the surviving papyrus is generally dated to the Twenty-First or Twenty-Second Dynasty, while the text's language and content point some scholars to an earlier Ramesside origin, so the span given here covers the wider Ramesside-to-Third-Intermediate range rather than a single agreed date.

Source Ancient Egyptian Literature, Volume II: The New Kingdom, Miriam Lichtheim tier 1

Instruction of Amenemope, Other Writings

Standing Scholarly debate

Concerns Era of Composition End Year

Currently States -1075

Egyptologists place the Instruction of Amenemope within the New Kingdom but disagree on the precise window: the surviving papyrus is generally dated to the Twenty-First or Twenty-Second Dynasty, while the text's language and content point some scholars to an earlier Ramesside origin, so the span given here covers the wider Ramesside-to-Third-Intermediate range rather than a single agreed date.

Source Ancient Egyptian Literature, Volume II: The New Kingdom, Miriam Lichtheim tier 1

Intinction, Practices

Standing Scholarly debate

Concerns Scholarly Note

Currently States Whether the shared cup is a practical arrangement or part of the sign itself is argued whenever an epidemic suspends it

Camps: one holds that the sign is the giving and receiving of the blood of Christ, so the vessel is a practical matter and intinction or individual glasses take nothing away. The other holds that one cup passed among many is itself saying something about the one body that separate vessels cannot say, so a substitution has a cost even when it is the right decision. Churches have taken both views, and some have taken both in successive years.

Source Baptism, Eucharist and Ministry, Faith and Order Paper No. 111, World Council of Churches, Commission on Faith and Order tier 1

Ior, Anglo-Saxon Futhorc Runes

Standing Scholarly debate

Concerns Origin of the Name

Currently States Old English ior, a word that occurs only as this rune-name. The poem describes a creature that lives surrounded by water and yet feeds on land; readings offered for it include the eel, the beaver and the world-serpent, and the poem names none of them.

Source The Old English Rune Poem: A Critical Edition, Maureen Halsall tier 1

Iota ⲓ, Alphabet Letters

Standing Scholarly debate

Concerns Origin Period

Currently States Greek letters wrote Egyptian from about the first century CE, settled by the fourth

According To The Coptic alphabet of Christian Egypt

The World's Writing Systems (Peter T. Daniels and William Bright, eds., Oxford University Press, 1996) surveys the small corpus of Old Coptic texts, pre-Christian magical and astrological papyri in which Egyptian was first written out using Greek letters plus a few signs borrowed from Demotic, against the standardised Coptic used in Christian scripture translation from around the third century CE onward. Comparing the two corpora, its contributors find the evidence thin enough to support two readings: that the Old Coptic magical texts already fixed the practice of writing Egyptian in Greek-based letters, or that the Christian translation project, needing a stable and teachable orthography for scripture, was the decisive act that standardised the script that survives. Because both readings draw on the same handful of surviving texts and no source describes an official act of decision, the volume treats the question as open rather than favouring either camp.

Source The World's Writing Systems, Peter T. Daniels and William Bright (eds.) tier 1

Iran-Iraq War, Wars & Conflicts

Standing Scholarly debate

Concerns Religious Dimension

Currently States Historians divide over how far the Iran-Iraq War was a sectarian, Sunni versus Shia, war. The broader scholarly consensus, argued by Efraim Karsh among others, holds that the war was fundamentally a territorial and interstate power dispute over the Shatt al-Arab waterway and regional dominance rather than a sectarian one, pointing to Iraq's own Shia majority population's continued loyalty to the Iraqi state through the war as evidence against a straightforward sectarian reading. A sectarian-framing camp, argued by Vali Nasr among others, holds that Ayatollah Khomeini's revolutionary government explicitly framed the war and its project of exporting the Islamic revolution in sectarian and pan-Islamist Shia terms, appealing directly to Iraq's Shia majority to rise against the Ba'athist government, while Saddam Hussein's government in turn invoked long standing Sunni Arab anxieties about Persian and Shia influence to rally domestic and regional Arab support, so that a real sectarian register was in play even though it did not determine Iraqi Shia loyalty. This atlas records both readings; the territorial-nationalist account is the broader scholarly consensus.

Source The Shia Revival: How Conflicts within Islam Will Shape the Future (Nasr), Vali Nasr tier 1

Iran-Iraq War, Wars & Conflicts

Standing Scholarly debate

Concerns Death Toll Minimum

Currently States 405000.000000

The lower, demographically skeptical bound: sociologist Charles Kurzman checked the widely cited Iraqi and Iranian government casualty figures, 250,000 Iraqi dead and 155,000 Iranian dead, against each country's own 1990s census data and found no reason to expect the true toll exceeds that combined total, roughly 405,000.

Source Death Tolls of the Iran-Iraq War (Kurzman), Charles Kurzman tier 2

Iran-Iraq War, Wars & Conflicts

Standing Scholarly debate

Concerns Death Toll Maximum

Currently States 1250000.000000

The higher, widely used academic dataset estimate: the Correlates of War Project's own coded battle death totals record approximately 500,000 Iraqi and 750,000 Iranian dead, a combined 1,250,000. The two named estimates reflect different methods, government-and-paramilitary tallying against a standardized cross-national coding scheme, rather than a single disputed number.

Source Correlates of War Project: Battle Deaths Data, Correlates of War Project tier 1

Iran-Iraq War, Wars & Conflicts

Standing Scholarly debate

Concerns Death Toll Assessment

Currently States Two independently derived figures are recorded rather than one disputed number: sociologist Charles Kurzman's demographically skeptical check of the Iraqi and Iranian governments' own casualty claims against each country's 1990s census data, roughly 405,000 combined, as the lower bound; and the Correlates of War Project's standardized cross-national battle-death coding, about 1,250,000 combined, as the higher, methodologically different estimate. The war's religious framing is itself a live historiographic question: Saddam Hussein's Iraq fought the war primarily over territorial and Arab-nationalist grievance (the Shatt al-Arab waterway, Khuzestan), not confessional difference, even though Iran's post-revolutionary Shia Islamist government and Iraq's Sunni-led Ba'athist state gave the war a Sunni-Shia coloring that later sectarian historiography has sometimes read back into the conflict's own causation more strongly than the belligerents' own stated war aims support.

Source Death Tolls of the Iran-Iraq War (Kurzman), Charles Kurzman tier 2

Irenaeus, Figures

Standing Scholarly debate

Concerns Lifespan or Floruit Start Year

Currently States 130

The source gives this year as about, its own approximate estimate rather than a fixed date.

Source The Oxford Dictionary of the Christian Church, 3rd revised edition, F. L. Cross and E. A. Livingstone (eds.) tier 1

Irenaeus, Figures

Standing Scholarly debate

Concerns Lifespan or Floruit End Year

Currently States 200

The source gives this year as about, its own approximate estimate rather than a fixed date.

Source The Oxford Dictionary of the Christian Church, 3rd revised edition, F. L. Cross and E. A. Livingstone (eds.) tier 1

Iri ੲ, Alphabet Letters

Standing Scholarly debate

Concerns Origin Period

Currently States Sikh tradition credits Guru Angad, the second Guru, with giving the script its settled form in the sixteenth century

According To The Gurmukhi script

Two reference works give incompatible accounts. The Encyclopaedia of Sikhism (Harbans Singh, editor-in-chief, Punjabi University, Patiala, 1998) carries the Sikh tradition that Guru Angad, the second Guru (1504-1552), devised the script. The World's Writing Systems (Peter T. Daniels and William Bright, eds., Oxford University Press, 1996), surveying the paleography of Indic scripts, holds instead that the letterforms were already in mercantile use in the Punjab as one of the Landa scripts descended from Sharada, and that comparing those existing Landa forms against the Gurmukhi letters attested from Guru Angad's era shows a fixing and standardising of a repertoire already in circulation rather than an invention from nothing. Neither side has displaced the other because the two accounts read different kinds of evidence, a community's own historical memory against a comparative script lineage, and the atlas records both without adjudicating.

Source The Encyclopaedia of Sikhism, Harbans Singh (editor-in-chief) tier 2

Iri ੲ, Alphabet Letters

Standing Scholarly debate

Concerns Origin Period

Currently States Historians of Indic writing place the letterforms earlier, in the Landa mercantile hands already used across the Punjab

According To The Gurmukhi script

Two reference works give incompatible accounts. The Encyclopaedia of Sikhism (Harbans Singh, editor-in-chief, Punjabi University, Patiala, 1998) carries the Sikh tradition that Guru Angad, the second Guru (1504-1552), devised the script. The World's Writing Systems (Peter T. Daniels and William Bright, eds., Oxford University Press, 1996), surveying the paleography of Indic scripts, holds instead that the letterforms were already in mercantile use in the Punjab as one of the Landa scripts descended from Sharada, and that comparing those existing Landa forms against the Gurmukhi letters attested from Guru Angad's era shows a fixing and standardising of a repertoire already in circulation rather than an invention from nothing. Neither side has displaced the other because the two accounts read different kinds of evidence, a community's own historical memory against a comparative script lineage, and the atlas records both without adjudicating.

Source The World's Writing Systems, Peter T. Daniels and William Bright (eds.) tier 1

Irish Confederate Wars, Wars & Conflicts

Standing Scholarly debate

Concerns Death Toll Minimum

Currently States 400000.000000

William Petty's 1650s Down Survey, the era's only systematic contemporary count, put total deaths from war, famine and plague across 1641 to 1652 at not less than four hundred thousand. Lenihan and other modern historians still cite this as the traditional low bound even while treating Petty's own method, extrapolating from incomplete surveys and never separating war deaths from famine and plague mortality, as unreliable for a precise total.

Source Confederate Catholics at War, 1641 to 1649, Padraig Lenihan tier 1