Not to discourage further discussion, but similar questions have been asked before. You may want to check out the answers in these questions:

• Why does Romania speak a Romance language but none of the rest of Eastern Europe does?
• How did it end up that Romanian, a romance languge, is spoken in n area completely surrounded by slavic/hungarian, cut off from all other romance languages?
• How did the Romanian language(a Latin based Romance language) come to exist and thrive in a region which is heavily dominated by languages with Slavic origin?

Also, you may want to try asking in /r/linguistics as this may fall under their purview as well.