The simple and short answer is that modern Hungarians are genetically descended from the pre existing population such as the romanized Dacians, Avars, and Slavs. Modern populations of hungarians were compared to skeletal remains and of the 100 people sample none of the people exhibited haplogroup N that was found on the remains.

This means that the original Magyars may have melted into a larger native population.

Side note Many of the cattle herding traditions my be a relic of pre magyar traditions.

Annals of Human Genetics. 72 (4): 519–534.