The Tat people (also: Tati, Parsi, Daghli, Lohijon, Caucasian Persians, Transcaucasian Persians) are an Iranian people, presently living within Azerbaijan, Armenia, and Russia (mainly Southern Dagestan).

Tats use the Tat language, a southwestern Iranian language. Azerbaijani and Russian are also spoken. Tats are mainly Shia Muslims, with a sizeable number of Sunni Muslims.

The earliest mention of Persians in the Caucasus is found in the Greek historian Herodotus' account of the Achaemenid expansion of 558-330 BC, during which they annexed Transcaucasia(South Caucasus) as the X, XI, XVIII and XIX satrapies of their empire.

Archaeological material uncovered in present-day Azerbaijan, Armenia and Georgia include Achaemenid architecture, jewelry and ceramics.

There is little information about permanent Persian population in South Caucasus since the Achaemenid period. Likely the ancestors of modern Tats settled in South Caucasus when the Sassanid Empire from the 3rd to 7th c. built cities and founded military garrisons to strengthen their positions in this region.

The Caucasus, also Caucas or Caucasia (for endonyms, see below), is a geopolitical region at the border of Europe and Asia, and situated between the Black and the Caspian sea. It is home to the Caucasus Mountains, which contain Europe's highest mountain, Mt. Elbrus. Politically, the Caucasus region is separated between northern and southern parts.

The northern portion of the Caucasus is known as the Ciscaucasus and the southern portion as the Transcaucasus.

The Ciscaucasus contains the larger majority of the Greater Caucasus Mountain range, also known as the Major Caucasus mountains. It includes Southwestern Russia and northern parts of Georgia and Azerbaijan.

The Transcaucasus is bordered on the north by Russia, on the west by the Black Sea and Turkey, on the east by the Caspian Sea, and on the south by Iran. It includes the Caucasus Mountains and surrounding lowlands. All of Armenia, Azerbaijan (excluding the northern parts) and Georgia (excluding the northern parts) are in South Caucasus.