Isenburg-Birstein was a country of southeastern Hesse in Germany.
It consisted of two German historical states. The first "Isenburg-Birstein" was a County and was created as a partition of Isenburg-Büdingen-Birstein in 1628. The second "Isenburg-Birstein" was a Principality, created as a partition of Isenburg-Offenbach in 1711. In the 19th century it was renamed in "Principality of Isenburg".

Now is "Isenburg-Birstein" called Birstein and it is a municipality in the state of Hesse, with 6223 inhabitants.

Unfortunatly there a limited information about Isenburg-Birstein