I think it's innacurate to state that the British created "artificial" tribes in Africa and Asia. Yes there was a lot of divide and rule but the British did not create tribes in their empire.
Then you actually know nothing about the history of the British colonial empire. Before colonial rule most things that became known as tribes were very fluid, you could pass onto one group to another without much of a problem.
The imposition of clearly defined ethnic tribes was used as an administrative tool during indirect rule. Basically there were not enough whites to administer certain colonies while at the same time the colonies lacked funds. So in order to compensate for this the British essentially ruled through chiefs who ran the day to day administration of the colonies.
Before colonialism many chiefs had nothing more than symbolic power and actually had very little power while in other societies chiefs simply did not exist. So the British ended up designating districts to be ruled by chiefs who were given absolute power, something which had not existed before in many societies while at the same time new chiefs were created for societies which previously had non before.
When it comes to the creation of "tribes" the British found a continent which was not homogenous and with many groups actually being mixed or not affiliated with anyone. In order to facilitate effective rule they deliberately used a policy of divide and rule, people were designated chiefs based on very narrowly defined "ethnic groups". Whereas before African societies had been extremely fluid what the British brought was a system whereby you defined to be part of a certain tribe, which was really important as it defined where you could live, who you paid taxes to, who you could marry, where you could own land,etc,etc.
In other societies certain "tribal" groups came about in different ways. For example in South Africa the creation of Zulu and Xhosa came about as a direct result of mining. Both Xhosa and Zulu are a part of a single Nguni language and "ethnic" group with many local dialects. The truth is that there is no one Xhosa group with many being Thembu, Fingo, etc the same being for Zulu who also have many distinct groups with their own local dialects and groups many of which were never unified and actually fought on opposite sides during colonial wars. However with the growth of the mining industry and the need for black labour it became increasingly useful for Whites to designate their labour pool based on where their workers came from. Thus all Nguni language speakers from the Natal Colony were designated as Zulu while all those who came from the Cape of Good Hope were Xhosa, those from Basotholand were Sotho and they were segregated in the compound system according to these very loosely defined "tribes" even though at the time there was no such thing as a Zulu or Xhosa "nation".
In other places like Rwanda the distinction between Tutsi and Hutu was purely based on whether you practiced pastoralism or were an agriculturalist.
So the real reason Africans and non whites are defined as belonging to tribes is a direct result of colonial rule.