Lemnia is crossed by national road DN11 [ro] (part of European route E574), which starts in Brașov, passes through Târgu Secuiesc and Onești, and ends in Bacău.

The village formed part of the Székely Land region of the historical Transylvania province.

In August 1940, under the auspices of Nazi Germany, which imposed the Second Vienna Award, Hungary retook the territory of Northern Transylvania (which included Lemnia) from Romania.

Towards the end of World War II, however, the commune was taken back from Hungarian and German troops by Romanian and Soviet forces in September–October 1944.

In 1950, after Communist Romania was established, Lemnia became part of the Târgu Secuiesc Raion of Stalin Region.