Supporting tribalism is haram in Islam. The prophet (saw) compared it to the acts of Jahiliyyah. The following hadiths shed some light on this matter:
It was narrated by Abu Hurairah that the Messenger of Allah (saw) said:
“Whoever fights under a banner of folly, supporting tribalism, or getting angry for the sake of tribalism, he dies in a state of ignorance.”
Grade: Sahih, Reference: Sunan Ibn Majah 3948
It was narrated that Jundab bin 'Abdullah said:
"The Messenger of Allah [SAW] said: 'Whoever fights for a cause that is not clear, advocating tribalism, getting angry for the sake of tribalism, then he has died a death of Jahiliyyah.'"
Grade: Sahih, Reference: Sunan an-Nasa'i 4115