Legend contends that the Lord Buddha or Sakyamuni he is no longer called Siddhartha after reaching Buddha hood and determined to keep his achievement and teachings to himself, for others would not believe or comprehend. But his mind was altered by the appearance before him of Brahman, who urged him to preach what had he learned and help others along the same path. From that point on, until his death at age 80, the Buddha preached without any interval.
The Chinese transliterated Sakyamuni as Shakamuni, but this was later shortened to Shaka in both China and Japan. “Shaka” is another word for the Historical Buddha, for as a human, he was born into the Sakya clan, a tribe that ruled a small state that now it is located in Tarai ,Nepal near the border with India.
His companion ascetics were the first to become his disciples, and soon afterwards they too attained enlightenment -- in Sanskrit they are termed as the Arhan, an Indian word meaning "one who is creditable of receiving obeisance". Arhatship is the main objective of all who practice Theravada Buddhism.