The flag of Bohemia is a historic flag, which now forms part of the design in the modern flag of the Czech Republic. The flag, a horizontal bicolour, was based on the colours of the former monarchs of Bohemia.
The heraldic flag of Bohemia (the flag of Bohemia in the form of the flag with coat of arms) is described and drawn for example in the work of Jacob Koebel: Wapen des heyligen römischen Reichs teutscher Nation from 1545.[1] The even older description of this flag (13th century) can be read in the chronicle of Ottokar aus der Gaal (Otacher ouz der Geul, Ottokar von Steiermark) (* about 1265; † between 1318 and 1322): Die Steirische Reimchronik.[2]