Complex sentence: Its name was changed from Yuan Dadu's "Jiandemen" to "Deshengmen" during the early Ming dynasty, having the implied meaning that the Ming won the war against the Yuan Mongols by having strong ethics and morals.
Split into simpler sentences: Its name was changed from the original "Jiandemen" during the early Ming dynasty. The new name implied that the Ming won the war against the Yuan Mongols by having strong ethics and morals.