Nanak was the first of ten Gurus, and Sikhism as it now exists was built across their two centuries of succession, each Guru named by the last.
The line gave the community its institutions. The second, Angad, is associated with the Gurmukhi script in which the scripture is written; the fourth founded the city of Amritsar; and the fifth, Arjan, compiled the Adi Granth in 1604, gathering the hymns of the Gurus before him together with those of Hindu and Muslim bhakti poets such as Kabir and Ravidas. Arjan was executed under the Mughal emperor Jahangir in 1606, the first of two Guru martyrdoms; the ninth, Tegh Bahadur, was executed in Delhi in 1675, in the tradition's account for defending the religious freedom of Hindus whose faith he did not share.
The tenth Guru, Gobind Singh, gave the community its most visible form. In 1699 he founded the Khalsa, an order of initiated Sikhs bound by a code and marked by the five articles of faith, uncut hair, comb, steel bracelet, sword and prescribed undergarment, commonly called the five Ks. And before his death in 1708 he ended the line of human Gurus, declaring that authority would pass not to a person but to the scripture itself, thereafter revered as the Guru Granth Sahib, the living and eternal Guru of the Sikhs.
From Nanak's teaching there grew, in this way, a community of some twenty-five to thirty million today, concentrated in the Punjab but present worldwide, whose central act of worship is the reading and singing of the words his successors preserved.