What parts of the world did the early expansion of islam spread to?

If  my mind serves me correctly Islam came to the Southeast Asia, first by the way of Muslim traders along the main trade-route between Asia and the Far East, then was further spread by Sufi orders and finally consolidated by the expansion of the territories of converted rulers and their communities. Hope this helps

disease was the number one killer of native peoples. they had had little exposure to the diseases of europe. this led to some villages being almost completely wiped out and some tribes destroyed.

a. "how old man winter was driven back” and “ormuzd and arimanes"