The early Vedic form of the Sanskrit language was far less homogenous compared to the Classical Sanskrit as defined by grammarians by about the mid-1st millennium BCE. According to Richard Gombrich—an Indologist and a scholar of Sanskrit, Pāli and Buddhist Studies—the archaic Vedic Sanskrit found in the "Rigveda" had already evolved in the Vedic period, as evidenced in the later Vedic literature. The language in the early Upanishads of Hinduism and the late Vedic literature approaches Classical Sanskrit, while the archaic Vedic Sanskrit had by the Buddha's time become unintelligible to all except ancient Indian sages, states Gombrich.