Halivakara is a kind of tax in the Gupta era. Halivakara was a plow tax, paid by every cultivator owning a plow.Some of its taxes include Bali, Bhoga, etc.
Nagarjuna was also termed as the Indian Einstein. He proposed the Theory of Relativity in his time in the form of a Sutra which is also called as the Prajna Parimata Sutra. He was a great patron of Mahayana doctrine.