Brahmanism was an early religion in the Indian sub-continent that was based on Vedic writing. It is considered an early form of Hinduism. Vedic writing refers to the Vedas, the hymns of the Aryans, who if they actually did so, invaded in the second millennium B.C. -- otherwise they were the resident nobles. In Brahmanism, the Brahmins, who included priests, performed the sacred offices required in the Vedas.

Brahmanism means to get united with the universal spirit (atman connected with parmatma) BRAHMA GYAAN. It has nothing to do with outside worldly things like wearing some yellow(pitamber) clothes or having a pony tail at head. As per shastra or historically brahmans had a freedom to have non-veg. Although food has got nothing to do with Brahma Gyaan. 

Brahma is a state of mind. To reach Brahma is to experience a connectedness with the harmony and balance within the universe, and especially on Earth.

History--Before IndiaBrahmanism comes from the Indo-Europeans, a migratory group from the Caucasus Mountains, between the Black and Caspian Seas. Many myths told by the Indo-Europeans traveled to Europe as well, and can be recognized not only in Indian mythology, but in Greco-Roman mythology.When the Aryans (what the Indo-Europeans called themselves in the Rig Veda—arya means “noble”) arrived in the Indus River Valley (modern day Pakistan), they encountered a once great society in the throes of decline, largely due to environmental degradation. We know little about the religion of the Indus Valley people, because we have only managed to translate about half of the words in their language, but at least one god, Shiva seems to come from the Indus River society.