{49:10} the believers are but brethren therefore make peace between your brethren and be careful of (your duty to) Allah that mercy may be had on you.

{3:103} And hold fast by the covenant of Allah all together and be not disunited, and remember the favors of Allah on you when you were enemies, then He united your hearts so by His favor you became brethren; and you were on the brink of a pit of fire, then He saved you from it, thus does Allah make clear to you His communications that you may follow the right way.

Comment: The religion of Islam as propagated by Prophet Muhammad (saws) led to the unification of all the warring tribes of Arabia.