It is said that the Hanbok worn by Koreans and Koreans originated in the Ming Dynasty. Then what kind of costumes did Koreans (aka Goguryeo) wear before the Ming Dynasty?

First, let me correct you, the Koreans before the Ming Dynasty were not Goguryeo, but Goryeo.

The ancient kingdom of Goguryeo was an ancient kingdom in China that rose in 37 BC and died in 668 AD.

250 years after the demise of Goguryeo, Sanhan people (Korean Peninsula natives) Wang Jian in the southern part of the Korean Peninsula to establish the Goryeo Kingdom, known as Wang's Goryeo, Korean Wang's Goryeo Dynasty originated from the name of Goguryeo, but this is two completely different countries rather than one continuous dynasty, because Wang's Goryeo and Goguryeo territory more than 95% does not overlap, different languages, the historical era span is too large (more than 250 years) This is a problem that must be strictly paid attention to in the study of Goguryeo's history. Therefore, Goguryeo is a local regime in Chinese history. It is not possible to be vague about the history, and this is one of the evidences to prevent Korean ultra-nationalists from coveting our northeastern territories, which must not be biased.

Wang's Goryeo was founded in 918 and was replaced by Lee's Joseon in 1392, spanning the middle of China's Five Dynasties to the early Ming Dynasty. Goryeo's culture before its submission to the Mongols in 1258 was largely derived from the Tang and Song dynasties, and its rituals, clothing, writing and so on were basically indistinguishable from those of the Tang.

The following picture is the portrait of Wang Jian, the founding king of Goryeo. The costumes are basically the same as those of the Tang and Song dynasties.

Wang's Goryeo submitted to Mongolia in 1258 after the cultural practices by the Mongolian influence, Mongolian clothing into Goryeo, but the aristocrats still revere the culture of the Central Plains, cultural traditions to retain.