The Romanian territory was inhabited in ancient times by the Dacians, an Indo-European people. They were defeated by the Roman Empire in 106 and part of Dacia (Oltenia, Banat and Transylvania) became a Roman province. For the next 165 years, there is evidence of considerable Roman colonization in the area, the region being in close communication with the rest of the Roman empire. Vulgar Latin became the language of the administration and commerce.
Under the pressure of the Free Dacians and of the Goths, the Roman administration and legions were withdrawn from Dacia between 271-275. Whether the Romanians are the descendants of these people that abandoned the area and settled south of Danube or of the people that remained in Dacia is a matter of debate. For further discussion, see Origin of Romanians.
Due to its geographical isolation, Romanian was probably the first language that split and until the modern age was not influenced by other Romance languages, which can explain why it is one of the most uniform languages in Europe. It is more conservative than other Romance languages in nominal morphology. Romanian has preserved declension, but whereas Latin had six cases, Romanian has three, the nominative/accusative, the genitive/dative, and the vocative, and retains the neuter gender as well. However, the verbal morphology of Romanian has shown the same move towards a compound perfect and future tense as the other Romance languages.
All the dialects of Romanian are believed to have been unified in a Common Romanian language until sometime between the 7th and the 10th century when the area was influenced by the Byzantine Empire and Romanian became influenced by the Slavonic languages. Aromanian language has very few Slavonic words. Also, the variations in the Daco-Romanian dialect (spoken throughout Romania and Moldova) are very small, which is quite remarkable. The use of this uniform Daco-Romanian dialect extends well beyond the borders of the Romanian state: a Romanian-speaker from Moldova speaks the same language as a Romanian-speaker from the Serbian Banat, indicating a relatively recent migration to the northern territories.
Romanian developed in isolation with regard to the other Romance languages. Therefore, it was influenced by Slavonic (due to migration/assimilation, and feudal/ecclesiastical relations), Greek (Byzantine, then Phanariote), Turkish, and Hungarian, while the other Romance languages adopted words and features of Germanic.