A little nugget on the wild horses featured in The Age of the Horse:

St Petersburg, 1900 (I believe): two young Przewalski horses or Takhi captured in Tibet are paraded for curious locals. They are gifts from the Grand Lama to Prince Hespère Ouchtomsky, “confidential friend of the reigning Tsar” and an aficionado of all things Asian. At the time, the Russian Empire was expanding east into Central Asia and beyond, troubling the British in their own imperial stronghold of India.
These photos come from volume eight of the “Travelogues” of American author Elias Burton Holmes, who was unimpressed by the horses:
Dazzled and for the moment docile, the animals, as we see them in the courtyard, do not uphold their reputation as the most savage of their kind; but the old man who came with them from Asia tells of many fearful things that these untameable brutes have done. Strangely enough, the very day these shaggy colts arrived – the first ever successfully exported – two representatives of Hagenbeck’s Menagerie reached Petersburg en route to Mongolia, their mission being to secure if possible a pair of these wild horses. I fear, had I been in the Prince’s place, I should have cut short the journey of the circus-men by turning over to them these embarrassing gifts of the Grand Lama.
I haven’t been able to find any mention of takhi captured in Tibet (if that is where they were caught) and am guessing that these horses did not survive long despite having made the long journey to St Petersburg.