Zalesye (Russian: Зале́сье; literally: "area beyond the forest") or Opolye (Опо́лье; literally: "area in the fields") is a historical region of Russia, comprising the north and west parts of Vladimir Oblast, the north-east of Moscow Oblast and the south of Yaroslavl Oblast. As a kernel of the medieval state of Vladimir-Suzdal, this area played a vital part in the development of Russian statehood.

The name alludes to the deep woods that used to separate the medieval Principality of Rostov from the Republic of Novgorod and the Dnieper principalities. Before the coming of Slavs in the 9th century, the area was inhabited by Merians, Muroma, and other Finnic tribes. In the 10–12th centuries these tribes were subsequently assimilated by the Slavic settlers.

In the twelfth century, this fertile area, being well protected from Turkic incursions by the forests, provided a favourable oasis for Slavic people migrating from the southern borders of Kievan Rus. The population of the area rapidly increased and by 1124 reached the point when Yuri Dolgoruki found it expedient to move his princely seat from Rostov in the Upper Volga Region to Suzdal in Zalesye.