Sorry for such a long wait, I didn't check this thread for a lot of time.
Some more reasons:
1: The archeologist Vasile Parvan discovered 2 documents from the 4th century, where a king from Transilvania is called "Jude". This is not a name given by the Byzantine empire (like "patriciu", "caesar", and others). This name has latin origin, so it's clear that the king ruled over latin people at the north of the Danube.
2: In all the documents, the Romanians are living in forests and mountains when the Hungarians came. Always in history the sedentary people retreat to live in the mountains when there is a danger in plains and grasslands, and surely not the people who came later start living in forests and mountains.
3: The Hungarians mention about "Codrii Vlasiei" which means "the forests of Vlasia". These forests occupied a lot of space in middle ages, but now there are only a few trees at the north west of Bucharest. My point is: in the language of the slavs, this means "the forests of the Vlachs" so the forests of the Romanians. Also the name Teleorman (in slavic Deli Orman) means in slavic languages "mad forest" so it's clear the people lived there!
4: I wrote in the other post about the kingdom of Gelu. In some languages (for example Greek) the letter "u" is written "ou", so his name could be Gelou. There is a big town near Cluj, called Ghilau (or Gilou), and it was a tradition in this area to give towns and villages names from kings.
5: But the most important reason is that all the names of the big rivers from Romania are very close to the original Dacian names, and this proves that there were people living in Romania always since the Dacian kingdom. So it's impossible that for several centuries nobody lived here, as the other theory sais (examples of rivers: Olt, Nistru, Prut, Siret, Buzau, Arges, Timis, Mures, Cris, Somes, Tisa, and many others. For example, the river "Olt" was called in Dacian "Alutus").
And I'm sure there are more reasons but I can't find them ATM.