Muhammad or Mehmud Shah, generally called Muhammad bin Islam Shah is believed to have been born in Daylam. He was almost ten years old when his father arrived in Kahek in 798/1396. If this is a genuine tradition, it implies that he was born possibly in 788/1386, and was about 17 years old while assuming the Imamate. He mostly resided in Shahr-i Babak in Kirman.
The Iranian Ismailis began to revert to their former settlements in different villages. Most of them engaged in agriculture in Kohistan, Qain, Birjand, Nishapur, Khorasan, Sirjan, Jabal-i Bariz, Mahallat and Yazd.
Muhammad bin Islam Shah seems to have started communications from his headquarters to different Ismaili communities, and also accepted the gifts of the pilgrims. It is said that the Indian Ismaili pilgrims were invested the title of 'darwish' (daras).
Taymur designated his grandson Pir Muhammad as his heir, who was about 22 years old in 807/1405. But, his cousin Khalil Sultan occupied Samarkand and was proclaimed as sultan. He was overthrown in 811/1409. Meanwhile, Shah Rukh (1409-1447), the fourth son of Taymur, the then governor of Herat, ascended as the next Taymurid ruler of Iran and Central Asia. He died in 851/1447 and was succeeded by his son Olugh Beg (1447-1449), who was in turn followed by Abu Sa'id (1451-1469).
One seminal point should not omitted here in discussion that the office of the hujjat or pir in India from Pir Shams (d. 757/1356) to Pir Hasan Kabiruddin (d. 853/1449) was almost hereditary, and then the office seemed to be revered like the hereditary office of the Imams, and therefore, an effect was necessary to enforce in the line of the pirs before the time it might become an ingrained belief. Thus, after the death of Pir Hasan Kabiruddin, Imam Muhammad bin Islam Shah designated his brother Pir Tajuddin, as a next hujjat or pir for Hind and Sind instead of any son, and one can hardly deny the logic springs from such designation.
Pir Tajuddin was most possibly born in 796/1394 in Uchh Sharif, and got his early education from his elder brothers. He was about 33 years old when designated as the next hujjat, or pir for subcontinent. The tradition relates that he used to put the bud of flower on his robe, making him familiar with the title of shah turrel (the lord of the tura or bud). He made Lahore as his centre because Uchh Sharif had become the ground of quarrel by his opponents. He had also an opportunity at Lahore to direct the descendants of Pir Shams in the mission works. He seems to have sent few dais in Afghanistan and Central Asia, whose detail is not accessible. Pir Tajuddin also preached in Sind, and once he had notably converted one Lohana family of 20 men, 18 women and 40 sons near Uchh Sharif, whose family head was Seith Lakhimal. Pir Tajuddin seems to have known as Prahlad among the Hindus of Sind because of his betrothal with a lady of Sodha tribe of Umarkot, and his descendants became also known as Prahlad, or Perraj. He seems to have composed some ginans, but only one is extant.
Sayed Imam Shah was a prominent dai in India. His name was Imamuddin, surnamed Abdur Rahim. He was born in Uchh Sharif in 834/1430, and was the younger son of Pir Hasan Kabiruddin. The tradition has it that when Pir Hasan Kabiruddin died, his all sons were present at Uchh Sharif with exception of Sayed Imam Shah. The tradition attests that he reached late during the interment of his father's body. Many traditions are recounted for his dissatisfaction, but all are legendary in character.
Sayed Imam Shah resided at Uchh Sharif with his sister called Bai Budhai, where he received a letter of Imam Muhammad bin Islam Shah through a certain Khoja Devasi Chandan. Hence, he started his journey for Kahek in 854/1450. Muhammad bin Islam Shah is said to have consigned him the mission for Gujrat. He returned and converted a bulk of Hindus in Gujrat. He got married to the daughter of Shah Muhammad Bakhri, who gave birth of Sayed Nur Muhammad Shah (d. 940/1534). Sayed Imam Shah died in 926/1520 and was buried in Pirana, situated ten miles south-east of Ahmadabad. It is said that he abjured Ismailism because of not succeeding his father, but it is not in conformity with the genuine traditions. Weighing up the extant evidences, it appears that he was ingrained in Ismailism and demonstrated unswerving loyalty to the Imams till his death, and never took any other route to goal his so called ambition. According to 'The Shorter Encyclopaedia of Islam'(Leiden, 1961, p. 167), 'As far as it is possible to ascertain, he cannot be regarded as the founder of a new sect, as he remained loyal to the Imam of his time.' He wrote many ginans which are recited by the Ismailis. He had four sons, viz. Sayed Alam Shah, Sayed Ali Shah, Sayed Bakir Shah and Sayed Nur Muhammad Shah, and a daughter called Shams Khatoon.
Returning to the thread of our main narrative, it appears that there are certain indications of the meeting between Muhammad bin Islam Shah and Shah Nimatullah (d. 834/1431), the chief of the Nimatullahis in Kirman. We have however no traces to confirm or contradict the above meeting.
Imam Muhammad bin Islam Shah died in Kahek in 868/1463, and was succeeded by his elder son, Mustansir billah II.