Just for fun a couple of decades ago I took the archaeology maps from “History of Transylvania”  and overlaid the Romanian ethnographic regions (the celebrated areas with old layers of Romanian folklore) on to the maps of archaeology sites for the various waves of invaders.
The history of Transylvania is particularly illusive, even though Transylvania was on the trade route from the Black Sea to Western Europe. There is a continuing (can never be proven) debate regarding the arrival of the Latin speaking Romanians; are they Romanised Dacians, or other Romanised peoples that moved there later, and if so, before or after the Magyars?
Köpeczi is one of the key works attempting to support the opinion that the Latin speaking people arrived there in the later medieval times, after the arrival of the Magyars (Hungarians). This book provides plenty of data, but its process of justifying an assumption linked to some notion is less than scientific.
My overlays do not prove anything, but could suggest that most of the invaders populated the valleys and lowlands, and so were separate from any peoples living in the mountains?
Goths and Gepids 3rd to 6th centuries
The Goths and Gepids (270-567) were Germanic peoples from southern Scandinavia who migrated south to around the Black Sea in the 3rd century AD. The frequent incursions of the Ostrogoths (from modern Ukraine) and the Visigoths (from around the Danube) into the Roman Empire caused the Romans to abandon Dacia in 270.
Huns 4th to 5th centuries
The rule of the Goths was ended by the Huns (375-453), a Turkic tribe coming from the plains east of modern Russia. The Huns under the leadership of Attila were a major military force in central Europe and their rule covered much of modern Hungary and Transylvania.
The Gepid leader, Ardaric, was a favoured ally of the Huns. After Attila’s death the Huns left Europe. The Gepids occupied the area east of the Tiza (now in Hungary and Romania) where they remained within the Hun kingdom. After the fall of the Huns they briefly ruled much of modern Romania until they were forced out by the Ostrogoths. They were subsequently defeated by the Romans and disappeared from history.
Avars 6th to 8th centuries
The Avars (552-796), another Asian-Turkic tribe from the east, took control of parts of southern Russia and Eastern Europe from the Huns and Slavs. They occupied most of modern Hungary with their empire stretching from the Black Sea to the Baltic, but in the 8th century their empire shrank and was finally ended by Charlemagne in 805.
Slavs from the 6th century
By the 6th century the Slavs were the largest European language group. Following the dissolution of the Hun Empire the Slavic peoples rapidly expanded populating modern Russia, Poland, Czech Republic, Slovakia, Croatia, Serbia, Macedonia, Bulgaria, and Romania. Little remains of Slavic Romania apart from many place and river names, and possibly the voivode and administrative organisation used by medieval Romanians and also inherited by the Magyars in Transylvania.
The Bulgars, a Turkic tribe from the east, having been forced from their kingdom around the Black Sea, formed the First State of Bulgaria (680), as rulers of the Slavs. Their kingdom covered the Danube plain to the north (modern Romania) and south (modern Bulgaria). Later the state of Bulgaria was extended further south into Thrace and Macedonia. The Bulgarian rule extended briefly into Transylvania
Magyar (Hungarian) from the 11th century
Five Magyar tribes and two Kun tribes entered the Danube basin in 896, settling within modern Hungary. Although these tribes had co-existed with Turkic peoples in the Steppe for a long time, their language structure is distantly related to the Ugrian peoples which is linked to the Finns, Estonians, and peoples of Siberia. In the following centuries the Magyars extended their rule in all directions forming the country now called Hungary after its previous rulers, the Huns.
- Köpeczi, Béla, et al. (1994). History of Transylvania, Budapest, Akademiai Kiado.