Tensions in the region began to rise amid rising nationalism among both Georgians and Ossetians in 1989. Before this, the two communities of the South Ossetian Autonomous Oblast of the Georgian SSR had been living in peace with each other except for the 1918–1920 events. Both ethnicities have had a high level of interaction and high rates of intermarriage. Dispute surrounding the presence of the Ossetian people in the South Caucasus has been one of the causes of conflict. Although Georgian historiography believes that Ossetian mass migration to the South Caucasus (Georgia) began in the 17th century, Ossetians claim to have been residing in the area since ancient times and that present-day South Ossetia is their historical homeland. No evidence exists to back up the Ossetian claims of being indigenous to South Ossetia. Some Ossetian historians accept that the migration of Ossetian ancestors to modern South Ossetia began after the Mongol invasions of the 13th century, while one South Ossetian ''de facto'' foreign minister in the 1990s admitted that the Ossetians first appeared in the area only in the early 17th century. Since it was created after the Russian invasion of 1921, South Ossetia was regarded as artificial creation by Georgians during the Soviet era.