Final answer:
The Ibar River flows from Montenegro into Serbia, which is the country the river traverses besides its source country. Serbia was part of the breakup of the former Yugoslavia, establishing its sovereignty after historical events and ethnic tensions.
Step-by-step explanation:
The country that has the Ibar River flowing from Montenegro through it and into Serbia is Serbia. After Montenegro declared its independence in June 2006, it became a sovereign state with the Ibar River marking part of its border with Serbia.
The Ibar River is significant as it is part of the broader geography and hydrology of the Balkan Peninsula. Serbia, having the Ibar flow through it, is a country rich in history and geography, being located in the central and western part of the Balkan Peninsula. As it flows through Serbia, the region has experienced numerous historical events, including the breakup of the former Yugoslavia, and ethnic tensions leading to the establishment of several independent countries such as Montenegro and Serbia.