The history of math is a co-evolution of symbols and concepts. When a symbol encapsulates a concept, then one has a powerful growth spurt.
The plus sign is an example. So is the equal sign. So is the inequality sign. These symbols led to a huge spike upwards in math. The development in algebra was pushed by these symbols and vice versa.
Cajori’s History of Mathematical Notations teaches this.
Some Cajori books available for free.