The first indications of algebraic operations are found in Babylonian mathematics, which used pre-calculated tables to formulate and solve equations. These models were always positive, as they solved only real problems.
Greek mathematicians, on the other hand, developed geometric algebra. Diophantus of Alexandria is considered the father of algebra. His book, Arithmetica, is among the highest-level ancient arithmetic books, though only the first six of thirteen books have survived to today.