By Brahmins the Buddha means enlightened monks - not just someone from the Brahmin caste.
In this kalpa (aeon) it is said that 5 Buddhas will arise- hence it is considered a fortunate aeon. I'm not sure whether it is in the suttas but there is some evidence that during the Gautama (current) Buddha's time, kassapa Buddha's teachings were in existence. Buddha's chief rival, Ven Devadatta's disciples only apparently accepted the previous three Buddha's teachings. Also King Asokha was said to have worshiped Kashyapa Buddha's stupa, which since then have been lost, according to one of his inscriptions. So there is some evidence of the four previous Buddhas. One more to go- most monks in Sri Lanka hope for their disciples to meet the coming Buddha- Meteyya, Maithri Buddha.