At this point, however, we must address the clearly Tang-Chinese attributes that are present, even in the portrait of Friederike Maria Beer, the backdrop of which she affirmed was derived from a Korean artifact. 
The rider on the right wearing the bird-feather cholpung, for example, wears a grimace quite different from the calm and almost expressionless faces of the Koguryo murals: he looks more like one of the Four Heavenly Kings guarding a Buddhist temple than a nomadic hunter on horseback. 
Likewise, all the other figures also have the fatter Chinese face with a flatter, curvier nose, in contrast to the slender and calm Koguryo face with a straight nose. Koguryo figures in the tomb murals also characteristically have lean, angular bodies, unlike the Chinese body type with the round belly and non-existent neck.
This and other discrepancies leads to two possible conjectures: the first, that while the said vase was of Korean origin and inspired by Koguryo era, was made at a much later date by an artisan mimicking that time period. Only after the 7th century—after the fall of Koguryo—did Korea become China’s de facto vassal state, paying tribute and following Chinese customs, ideals, and apparel. Chinese style of art also became extremely popular; for example, many Korean artists of Chosun period depicted Chinese-looking sages in Chinese landscapes. This, however, does not explain the other crucial incongruity that Korean ceramics, Koguryo or no, are not inclined to portray ceremonial scenes. Most Koguryo ceramics do not have any design on them at all, and few later ones simply have geometric patterns. Patterned or plain, they certainly do not depict the life in Koguryo—what we know about Koguryo apparel and culture is almost entirely derived from the mural paintings, aided by ancient manuscripts. Likewise, later Korean ceramics portray floral, stylized and natural motifs, Taoist and Confucianist symbols, and landscapes—but not usually people, and certainly not ceremonial scenes: it was the Chinese who were more inclined to place humans on their ceramics. The conjecture that the vase was made by a Korean artisan of a later period is therefore possible but unsatisfactory, unless the artifact was not a vase at all, and some other form of Korean artifact.