Later Three Kingdoms
During its heyday, the country contested with Balhae, a Goguryeo–Mohe kingdom, to the north for supremacy in the region. Throughout its existence, Unified Silla was plagued by intrigue and political turmoil in its newly conquered northern territory, caused by the rebel groups and factions in Baekje and Goguryeo, which eventually led to the Later Three Kingdoms period in the late 9th century.