DBQ: Read the following excerpt to answer the question below Travels, Marco Polo, written in 1298 based on his travels from 1274 to 1290.
Their arms are bows, iron maces, and in some instances, spears; but the first is the weapon at which they are the most expert, being accustomed, from children, to employ it in their sports. They wear defensive armor made from buffalo and hides of other beasts, dried by the fire, and thus rendered extremely hard and strong. They are brave in battle, almost to desperation, setting little value upon their lives, and exposing themselves without hesitation to all manner of danger. Their disposition is cruel.
They are capable of supporting every kind of privation, and when there is a necessity for it, can live for a month on the milk of their mares, and upon such wild animals as they may chance to catch. Their horses are fed upon grass alone, and do not require barley or other grain. The men are trained to remain on horseback during two days and two nights, without dismounting…. No people on earth can surpass them in fortitude under difficulties, nor show greater patience under wants of every kind. They are most obedient to their chiefs, and are maintained at small expense.

To whom is Marco Polo referring to in this excerpt?

Byzantines
Russians
Romans
Mongols