This map can assist is finding which historical area your ancestor is from. The blue is Wallachia, The green is Transylvania, including the areas Crisana and Maramures. The Banat is also included in Transylvania and comprises the counties of Timis and Caras-Severin in the southwest of Transylvania. The red is Moldavia, including southern Bukovina in Suceava county. The yellow is Dobrogea. The current Republic of Moldova is also shown; historically, it was part of Moldavia. There follows some historical maps tracing the development of modern Romania:
The above map shows the Romanian principalities when they were united under Mihail Viteazu in 1600. Two centuries later, the principalities are still surviving, surrounded in a sea of empires, who still desire the Romanian lands. The biggest change is that the Russian empire has replaced the Polish one to the east. As of 1794, Poland no longer exists, itself being the victim of surrounding empires. Around 1800, here is how Romania looked:
This map shows the union of Wallachia and Moldavia, which occured in 1859. This is the first time the name "Romania" was used for the area. The united principalities were christened the KIngdom of Romania in 1878 by King Carol I, when Romania was recognized as an independent country by the Congress of Berlin. Dobrogea was added to the kingdom at that time.
This shows Romania at its greatest extent, between the two World Wars. There are a couple of errors in the map: the current Republic of Moldova does not include northern Bukovina or the area along the Black Sea. These were annexed to Ukraine in 1940, about the same time that southern Dobrogea was ceded to Bulgaria.