2000 is not a lot.
“Andrei Novikov (A Russian fellow) said in an interview for the Russian Interfax news agency: According to intelligence agencies, there are about 2,000 Russian citizens are fighting in the ranks of ISIS, and according to expert estimates, the number is about five thousand fighters.
Even 5,000.
Now, if one can say Turkey or France are supplying more, I’d look at the data.