Since when have Berbers ever been black?

Many Berbers have blond hair and blue eyes and look Southern European. These people have hardly mixed with Arabs and have been indigenous to North Africa even though many have accepted the cultures that the Arabs brought along. They even look more white than Phoenicians (Lebanese) who happen to be the fairest of the middle east and usually identify as white. So why do afrocentrists claim that they were black and still are black even though they look like any southern European and are phenotypically African? How can you really claim a blond Berber just because they are indigenous to Africa?