The interdisciplinary and cross-institutional cooperation in Berlin Mathematics goes back to the eighties, when ZIB was founded in 1984 and the Berlin Algorithms Day was first established in 1989. The first DFG Research Training Group in mathematics in Berlin was established between TU Berlin and WIAS in 1996. In 1998, all three universities joined forces with WIAS and ZIB to host the International Congress of the Mathematicians. This broad alliance of Berlin Mathematics shaped the future: In 2002, the DFG Research Center Matheon started and in 2006 the BMS was founded as part of the German National Excellence Initiative. In 2014, Matheon and BMS together with the DZLM (German Centre for Mathematics Teacher Education) successfully applied to collaborate in the Einstein Center Mathematics Berlin (ECMath) funded by the Einstein Foundation Berlin. The preliminary culmination of this development is the Berlin Mathematics Research Center MATH+, which is funded as a Cluster of Excellence in the framework of the German National Excellence Strategy since January 2019.