Again guys , I would say "Dominance Theory". Britain Ruled the world, made english language widely use.. so it because international language. K garne Gorkhali le kehi garna sakena.... nepali language lai international language banauna ko laagi... !!! Hindi is understood by many people in nepal ... K garne nepali le hindi bolne lai nepali sikauna sakena !! Jaslai je sajilo lagchha ani jaha jasle jasari bujhchha tyahi nai language use garnu upayukta hunchha... INTERNATIONAL language re yarr... k ko international ... ! japanese le bujchha international language english ? ( I AM TALKING ABOUT MOST OF THE POPULATION)... So .. jasle dominant garyo tyahi raja ho yo sansar ma ... it is natural theory .. Darwin le lekhisakeko chha yo kura uhile nai .. SURPRISE HUNU PARNE KARAN KEHI CHHAINA !!