"What we know is palm full; what we don't know is world full". So goes a Tamil saying.
This morning when I was watching "Dharma Sandehaalu" on Bhakti TV, I came to know of a very interesting info: King Yaso Varman who was ruling Khaambhoj province (present Cambodia) of ancient India (known as Bharatha Kanda at that time) had a son inflicted with some disease; this was because in his previous birth he did not do any good deeds though born in a Brahmin parentage with Dhaarmic value systems. In his attempts to get his son's disease cured, Yaso Varman let the prince observe Ratha Sapthami Vratha. This cleared the prince's disease and he became a monarch later.
Oddly enough, our school textbooks never mention any thing about contributions by Indians of ancient India.