Before the arrival of Islam in Minangkabau, this region had been colonized by several kingdoms, the first Kingdom that colonized Minangkabau is the Sriwijaya Kingdom, the conquest included the whole Sumatra, Alam Melayu and Jawa Tengah. They brought the influence of Buddha and Hindu, making it widely spread in its occupied territories. Since Minangkabau was under its territories for a very long time, the influence of Hindu-Buddha was very strong in society. As the empire is weakening later leading to their downfall, it is replaced by the Kingdom of Majapahit.

The arrival of Islam in Minangkabau happened in two ways. First, due to many Muslims from Indian subcontinents travel and do trading in which they depart on Minangkabau, as well as due to the expansion of Acheh power along the west Sumatran coast between Barus in the North and Indrapura in the South, where the small part of the kingdom was originally a part of Minangkabau kingdom. Especially in the era of Sultan Iskandar Muda, wherein the period of his reign can be considered as a very advance period in the field of religious inquiry and learning process, as well as the emergence of prominent scholars such as: Hamzah Fansuri and Nuruddin ar-Raniri.

Through this phenomena, many students from other country came to Aceh to learn Islam, and when they come back to their homeland, they become scholars not only to strengthen Islam but ultimately their own country too. Among the student who came to Aceh to seek knowledge was Sheikh Burhanuddin. He became a disciple of Abdur Rauf Singkili in which as he completed his study, he too returned back to his hometown and spreads his knowledge within his hometown Minangkabau. So, many students from different Nagari's in Minangkabau studying from him, Among them "Tunku Mansingah Nan Tuo", that later play some roles in Padri War.

Some interesting information about the arrival of Islam that can be shared based on book resources that I found, Sheikh Burhanuddin make Ulakan as a centre for his teaching and spread his teacher's thought which is Wihdatu Syuhud. And also Hamzah Fansuri followers that bring contrary thought with them, also head on Minangkabau and make Cengking as their centre.

Most of Minangkabau people prefer Hamzah Fansuri school of thoughts rather than Sheikh Burhanuddin because of his understanding are closer to Buddhism in which they believe that God is in ourselves. 

Three Volcano Mountain in straight line.
Other than that, the reason of why islam arrived a little bit late to Minangkabau compared to Aceh, even though both of it within one Peninsula, because its own geography, their have a line of volcano mountain (which consist of three mountains) , it seems like to block the communication between both country.

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Hamka, (1982). Ayahku. Jakarta: UMMINDA publication

Rais, Z. (2001). Against Islamic Modernism, The Minangkabau Traditionalist Response to The Modernist Movement. Jakarta Selatan: Logos Wancan Ilmu.

Hamka. (1985). Islam dan Adat Minagkabau. Jakarta: Pustaka Panjimas.