The breed of kings! The breed of horses for which the Chinese fought the War of the Heavenly Horses. From Wikipedia:
Emperor Wu of Han had received reports from diplomat Zhang Qian that Dayuan owned fast and powerful Ferghana horses known as the “heavenly horses”, which would help greatly with improving the quality of their cavalry mounts when fighting the Xiongnuhorse nomads, so he sent envoys to survey the region and establish trade routes to import these horses. However, the Dayuan king not only refused the deal, but also confiscated the payment gold, and had the Han ambassadors ambushed and killed on their way home. Humiliated and enraged, the Han court sent an army led by General Li Guangli to subdue Dayuan, but their first incursion was poorly organized and undersupplied. A second, larger and much better provisioned expedition was sent two years later and successfully laid siege to the Dayuan capital at Alexandria Eschate, and forced Dayuan to surrender unconditionally. The Han expeditionary forces installed a pro-Han regime in Dayuan and took back enough horses to improve Han’s horse breeding.
With respect to the Andalusian being derived for that, that is something that is highly highly debated. And there are three camps of people in this, the purest Andalusian people who beleive absolutely not. They think that the skies opened up and the Andalusian just dropped there. As if it had no breeding and adaptation. You can read sources from the Arab world which will tell you about the Barbs and horses from the Andalus region of North Africa that they took there to breed with Domestic stock. Now within those camps, you can also find the same references to where their horse breeds originated and you will find them breeding to Persian Nisean horses and domestic egyptian horses to get the modern Arab. …
And so on. Very interesting, and this person believes that the Nisean horse breed is not extinct at all, but remains in very much the original form in Iran. Similar to Andalusians, which are indeed a beautiful and striking breed.