Scholars and knowledgable have been aware coginizant of the spherical nature of the earth since pre-history.
Not since pre-history, but at least from classical times. I've come across comments the ancient Egyptians knew the shape of the Earth, but I have yet to find any substantiation for it. Pythagoras may have determined the shape of the Earth from the shadow it cast on the Moon during a lunar eclipse (which would put knowledge the Earth was a sphere as early as the fifth or sixth century B.C.).