Islam in Afghanistan began to be practiced after the Arab Islamic conquest of Afghanistan from the 7th to the 10th centuries, with the last holdouts to conversion submitting in the late 19th century. It was generally accepted by local communities as a replacement of budhism and local tribes began converting to the new religion. Islam is the official state religion of Afghanistan, with approximately 99.7% of the Afghan population being Muslim. Roughly 90% practice Sunni Islam, while around 10% are Shias. Most Shias belong to the Twelver branch and only a smaller number follow Ismailism.