What the hell are you talking about? What is a Vlach for a start?
They are an ethnic group much like the Slavs - Vlach is a word that germanic celts used to describe their neighbours primarily in central and south eastern Europe who had been converted by Romans and spoke a bastardised version of Latin which was the language of the Roman empire. Hence the term Romanian. Vlachs are also the majority ethnic group in neighbouring Moldova and have significant populations in the Ukraine, but also have small populations dispersed across Hungary, Serbia, Bulgaria.
The Vlachs are literally nothing to do with "Romas" or gypsies which are a completely separate tribe who appear to be Indian in origin. The only relationship is they happen to live in some of the same countries. Romania just happens to have one of the largest populations of Roma but by no means the largest - Spain, Brazil and the US all have larger Roma populations. However it probably feels like there are more in Romania because Roma make up 3.3% of the population only topped by Bulgaria at 4.7%.
So typically when you hear about crime related to Romanians it is Roma who just happen to be Romanian citizens legally. No surprise that Bulgarians and Albanians feature highly in our crime stats here as well given their Roma populations.
A recent study showed that significant portions of inmates in UK prisons identified themselves as gypsies / Roma / travellers - between 5-12%
. These came from a range of different countries including Irish travellers but the majority Roma.