Ink and colours. A black horse and a white horse are cantering with a Central Asian groom mounted on the latter, holding the black horse by its rein.  The groom's facial hairs, the mane of the mounts as well as the garment folds are all done in fine, sinewy brushwork with not a single hair out of place.
The work is unsigned.
To the upper left an inscription reads:
Genuine work by Han Kan.  Inscribed by the Imperial Hand in the ting-hai year (110 A.D.)
This is followed by one imperial seal: Hsuan-ho.  In the upper right there is the gourd-shaped imperial seal.
While unsigned, the brushwork of the calligraphy appears to be that of the Sung Emperor Hui-tsung.
Han Kan (active 8th century) was a native of Lan-tien in Shanhsi Province.  The Record of Famous Paintings and the History of the Tang dynasty however both report that he was a native of Ta-liang, modern Kai-feng in Honan Province.  The Sung catalogue Hsuan-ho hua-pu and the Yuan treatise Tu-hui pao-chien both say that he was a native of Chang-an.  He was known for his painting of figures, Buddhist subjects, deities, goblins, and excelled in the painting of horses.  He first studied the manner of Tsao Pa, but later developed a style of his own. In the early Tien-pao period (742-755 A.D) he entered Court service in the Office of ssu-cheng of the Imperial treasury.  Once the emperor ordered him to study from the horse paintings of Chen Hung, but he did not obey.  The emperor wondered why and asked him, whereupon Han replied, "Your servant has his own teachers.  All the horses in Your Majesty's stables are my teachers."  He established a personal style all his own.  The dates of his birth and death are not known.