Multilingual and Multiregional SEO

I would like to ask, all the webmasters here, a question! How can we target our Multilingual website in different regions? We have created sub-directories for Multilingual websites, like abc.com/en-us, & abc.com/ru_ru/
Kindly tell me how I can do SEO for different URLs in different regions. Right now I am using hreflang tag for every page. Do I still need backlinks from multilingual websites? For example, for abc.com/ru_ru/, do I need back-links from russian websites ?