The other way around. We started with base 20 everywhere then simplified some of it.

During medieval times it used to be :
10 Dix (10)
20 Vingt (20)
30 Vingt et dix (20+10)
40 Deux-vingt (2x20)
50 Deux-vingt et dix (2x20+10)
60 Trois-vingt (3x20)
70 Trois-vingt et dix (3x20+10)
80 Quatre-vingt (4x20)
90 Quatre-vingt et dix (4x20+10)

Then they switched to base 10... But only up to 70 for some reasons in France. Belgium and Switzerland (and some parts of France) have gone all the way to 100 by using Septante (70), Octante or Huitante (80) and Nonante (90).