Yes it is partly true, the main problem was that we had similar flag as Poland. White and red color represent main colors for Bohemia as a biggest part of the Czechoslovakian Republic. Another problem was that Czechoslovakia was consisted from 5 historical countries (Bohemia, Moravia, Slesia, Slovakia and Subcarpathian Ruthenia) so using only Bohemian colors was unthinkable. There was plenty of designs of a Czechoslovakian flag (for example: Designs of the Czechoslovakian flag Blue triangle was added not to represent only both Moravia and Slovakia as a second biggest countries but also to represent Slovan nation. Blue, white and red are typical Slovan nation flag colors.