The Portuguese were successful at imposing new identities
Every enslaved African in any far-away land colonized by Europeans was the bearer of a new identity, according to the whims of the slave masters. But because no other country secured slaves from different parts of the continent than the Portuguese, their task of imposing new identities was different.
Interestingly, the Portuguese overcame this task in spite of the fact that Portuguese had among their stock enslaved peoples from Mauritania in northwest Africa to Mozambique in southern Africa.