Their are many regional languages website and blogs are running successfully these days. But their is limitations. Because their are less advertisers available. Even i saw few adverts in hindi and urdu on few websites. But i never saw google adsense adverts on regional websites. You can check one regional hindi language portal Webdunia. You can read this website in English, Hindi, Tamil, Gujrati, Marathi, Punjabi, Kannada, telugu, and malayalam. This website is stunning and presented well and monetize by CPM type of adverts.
Hence, monetization of regional blogs is also possible easily. If you write in regional blogs/websites. You can choose necessary ad networks from india too.
Ads For Regional Websites: You can see that this website is using CPC ads for its monetisation. hence making money for regional language peoples will be easy. if they use adsense for their content.
Check Here Google ads for hindi website. May be they remove these ads in future. If their is no google ads in future then comment below.