People very much overestimate the Mongolian ability to overpower western Europe. The Holy Roman Empire is led by one of it's younger more vigorous monarchs who could plausibly hold his tactical ground, Germany is one of the most fortified areas in the world at this point in history with dozens of castles which while the Mongols are almost certainly capable of capturing them would be a long painful bloody slog to do so (and even the comparatively Mongol friendly terrain of Hungary still gave them trouble with the fortified points), and the Mongols are still led by an extremely old obese man who is going to die any day by that point.