Sihlea is situated on the border with Buzău County, only 17 km (11 mi) from Râmnicu Sărat.

In the north, it is also crossed by the national road DN2N [ro], which connects it to the east with Tătăranu (where it ends in DN23A [ro]) and to the west with Dumbrăveni (where it intersects with the same DN2), Bordești, Dumitrești, Chiojdeni, and Jitia.

The partly built A7 motorway, which starts in Ploiești in the direction of Buzău, will enter Vrancea County in Sihlia, continuing north towards Focșani and ending in Siret.

[2] Train stations in Voetin and Sihlea villages serve the CFR Main Line 500, which connects Bucharest with the Ukrainian border near Chernivtsi.

According to the 2011 census, the commune had a population of 5,039, of which 90% were ethnic Romanians and 5.9% were Roma.