Posavina, also called Bosanska Posavina, is in Bosnia and Herzegovina.
Bosanska Posavina is the northeastern region of Bosnia and Herzegovina, lying along the Sava River. Larger Posavina region extends well beyond Bosnia's borders, occupying parts of Slovenia, Croatia, and Serbia lying in the basin of Sava.
Bosanska Posavina was badly hit by the Yugoslav Wars of 1992–1995 in the extreme: The region became virtually deserted, as the locals fled to the adjacent regions and most of their homes were destroyed. Only a small fraction of former inhabitants returned since.
The region traditionally had a Croat majority, while today it is predominantly inhabited by the Serbs.
As most of inhabitants of the region are of Serbian descent today, Serbian is the main language in the region. Although Croatian, and Bosnian are mutually intelligible with Serbian as most of the differences between three languages are academic, be ready to decipher some Cyrillic as it is the script of choice amongst Bosnia's Serbs.