Guru Arjan (1563-1606), the youngest son of Guru Ram Das and Guru from 1581, presided over the Panth as it took on the form of a settled, organised religion. He completed his father's city of Amritsar and raised at the centre of its sacred pool the Harmandir Sahib, the Golden Temple, giving it, by tradition, four doors opening to the four directions, a built statement that it stood open to all castes and all peoples.
He founded further towns, among them Tarn Taran and Kartarpur, and organised the community's finances through the masand system, a network of local deputies who gathered the offerings of the faithful and remitted them to the centre. Under his leadership the Panth grew markedly in numbers, wealth and visibility, a prosperity that was itself, in time, to draw the attention of the Mughal state.
Guru Arjan's central achievement was textual: in 1604, working at Amritsar, he compiled the Adi Granth, drawing together the hymns of his four predecessor Gurus with his own extensive compositions and, deliberately, with verses by Hindu Bhakti and Muslim Sufi poets outside the Sikh line, among them Kabir, Ravidas, Namdev and Farid, a decision that fixed the scripture's inclusive character from its first assembly. He installed the completed volume in the Harmandir Sahib and appointed Baba Buddha its first reader.
His prosperity drew the suspicion of the Mughal court. In 1606, under Jahangir, who records the episode in his own memoir, Arjan was arrested, fined and tortured to death at Lahore, for supporting the rebel prince Khusrau and for his growing following; he is remembered as Sikhism's first martyr.