The Scythians, also known as Scyth, Saka, Sakae, Sacae, Sai, Iskuzai, or Askuzai, were a large group of Iranian Eurasian nomads who were mentioned by the literate peoples surrounding them as inhabiting large areas in the central Eurasian steppes from about the 9th century BC until about the 1st century BC. The Scythian languages belonged to the Easternbranch of the Iranian languages. The "classical Scythians" known to ancient Greek historians were located in the northern Black Sea and fore-Caucasus region. Other Scythian groups documented by Assyrian, Achaemenid and Chinese sources show that they also existed in Central Asia. Although ancient Persian sources also used Saka to refer to the Western Scythians of the northern Black Sea, modern scholars usually use the term Saka to refer to Iranian-speaking tribes who inhabited the Eastern Steppe and the Tarim Basin.

The relationships between the peoples living in these widely separated regions remains unclear. The term "Scythian" is used by modern scholars in an archaeological context for finds perceived to display attributes of the "Scytho-Siberian" culture, usually without implying an ethnic or linguistic connotation. The term Scythic may also be used in a similar way, "to describe a special phase that followed the widespread diffusion of mounted nomadism, characterized by the presence of special weapons, horse gear, and animal art in the form of metal plaques".Their westernmost territories during the Iron Age were known to classical Greek sources as Scythia.

The Scythians were among the earliest peoples to master mounted warfare. In the 8th century BC they possibly raided Zhou China.Soon after they expanded westwards and dislodged the Cimmeriansfrom power on the Pontic Steppe. At their peak, Scythians came to dominate the entire steppe zone, stretching from the Carpathian Mountains in the west to central China (Ordos culture) and the south Siberia (Tagar culture) in the east,creating what has been referred to as the first Central Asian nomadic empire.

Based in what is modern-day Ukraine, Southern European Russia, and Crimea, the western Scythians were ruled by a wealthy class known as the Royal Scyths. The Scythians established and controlled a vast trade network connecting Greece, Persia, India and China, perhaps contributing to the contemporary flourishing of those civilizations.