The nine walis were Sufi teachers who spread Islam and did all variety of powerful and unusual acts across Java. The histories of these men are not always clear. In fact, if you try to count all of them, you will end up with more than nine.
Some sources say that there was more than one group of nine.
The most probable explanation is that there was a loose council of nine religious leaders, and that as older members retired or passed away, new members were brought into this council. Symbolically, for later rulers on Java, the wali songo provided a link between the rulers of Majapahit or earlier kingdoms, and the rulers of Mataram, and eventually the Sultans of Yogya and Surakarta. They were both links in the dynastic family trees and cultural links, as they adapted the old arts and traditions to the new Islamic reality. Sunan Gunungjati worked at Demak and Banten, and was the founder of Cirebon. Many stories say that he was originally from Pasai in Aceh, others say that he was from Pajajaran in West Java.