White lions are African lions (or whatever subspecies they were born as) just with white coloration. As others have said the reason Kimba doesn't live in a pride like a normal lion (white or otherwise) is the story didn't call for it. And if he did live in a pride he wouldn't be in charge whoever the lead male of the pride was would be and a pride of lions might not be as open to Kimba's new ideas as the other (mostly prey) animals were. (I only have a DVD with only a few episodes on it so my knowledge of Kimba is very limited).