The number (and the total inconsistency with how many people actually
protested) comes from here:
http://www.indianexpress.com/news/protest-against-wrong-map-mars-countrys-first-wiki-conference/877826/0
in which it simultaneously describes "hundreds of protesters" *and* that
"all 21 who protested were arrested".
Go figure.
The article that's been created out of the controversy is a storm in a
teacup (and as such is hardly notable) but the storm was so small it was
barely noticeable - and would have stayed that way except for the
misreporting of it.
I must say I was slightly disappointed at the size of the protest. We heard the protest begin, we went around asking all attendees standing outside to enter the convocation hall; by the time we reached the gate from the lawns, the protesters had already been swept into a police van and were about to leave.
To be fair, they were far outnumbered by the police.