This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Families gathers twelve established language families the atlas draws on, from the first ever demonstrated by the comparative method to one whose very unity is still argued over.
Indo-European, reaching from Ireland to Bengal, was the first family demonstrated, in the late eighteenth century, and its reconstructed vocabulary remains the chief evidence for the religion of peoples who left no texts. Afro-Asiatic, spanning North Africa, the Horn and the Middle East, is among the oldest securely established families and the least settled internally, its branches having diverged early enough that shared inheritance is thin. Sino-Tibetan produced two of the largest religious canons ever assembled, Chinese and Tibetan, with the structure connecting them still being worked out. Niger-Congo, the largest family in the world by language count, is itself disputed: the Bantu core is beyond question, but whether Mande, Ubangian and some Atlantic groups truly descend from one ancestor is argued, and some specialists treat the name as a working label rather than a demonstrated family.
Austronesian spread wider than any family before 1500, from Madagascar to Easter Island. Dravidian's relationship to the undeciphered Indus Valley script has been proposed repeatedly and never shown. Quechuan is the only family here whose expansion was driven twice by religious administration, first the Inca state, then Spanish missionaries. Mayan, Uto-Aztecan, Turkic, Uralic and Algonquian complete the twelve, each carrying its own peoples' distinct ceremonial and textual traditions rather than one shared religion.