
1,800 BCE
The Stone Tablet
A stone tablet was written in ancient Babylon that includes some of a simplified version of algebra. The tablet did not include any of the symbols we use now in common day. The Babylonians had methods for solving quadratic equations. 
820
The Meaning of Algebra
The word Algebra was written in Medieval Latin which came from a book written by al Khwarizmi in 820 AD. Also the word algebra is an Arabic word, ¨Al Jabr¨ which means, ¨the reduction¨. The books also explained that in order to solve an algebraic expression you must do the same operations to both sides. 
Begriffsschrift
One of the founders of modern logic who was German named Gottlob Frege who contributed in a book called Begriffsschrift. The book Begriffsschrift is about logic calculus which was written by the founding father. 
John Horton Conway
A British man named John Horton Conway made important contributions to the Game Theory. As well as many other theories like the group theory, number theory, geometry and (especially) recreational mathematics. 
Period:570 BCEto495 BCE
Pythagoras
A greek man named Pythagoras discovered a simplified version of geometry, or how to solve square and triangular numbers. Him and his followers used geometric and visuals to help solve certain equations. 
Period:200to284
Replacing Statements with Symbols
A man named Diophantus was a mathematician who created a book series of books called ¨Arithmetica¨. His books include the first suggestions of Algebraic Notations. Diophantus began replacing words with symbols in order to solve algebraic equations. 
Period:598to665
Bhaskara and Brahmagupta
A man named Bhaskara decided to try to replace the unknown identities in an algebraic equations with letters somewhere between 598 AD  665 AD. While a man named Brahmagupta discovers a certain way to solve types of Equations in India. 
Period:1540to
The Use of Addition and Subtraction
A man named Francois Viete tried using letters to replace the unidentified numbers in an equation like Diophantus. Then he started to the +/ signs to represent addition and subtraction in an equation. This made equations easier to understand and more efficient. 
Period: to
Niels Henrik Abel
A man named Niels Henrik Abel discovered that there is no general formula to solve that can solve all quintic equations. He proved that there was no general way to solve any quintic equations. Along with group theory, abelian groups, and abelian categories. 
Period: to
Évariste Galois
A french man called Évariste Galois proved that there was no algebraic method to solve polynomial equations of a degree larger than four. He also proved there was no algebraic method to solve, laid groundwork for abstract algebra, Galois theory, group theory, and the ring theory, etc.