Microsoft launched Bing in 2009 to replace Live Search. Microsoft officially released Bing on June 3, 2009, after announcing the transition from Live Search in May of that year.
Bing was the latest name in a sequence of Microsoft search products. It followed MSN Search, Windows Live Search, and Live Search as Microsoft tried to build a stronger identity in the search market. The new branding was intended to be short, memorable, easy to spell, and associated with the moment of finding an answer.
Kumo was an internal development codename associated with the project, not the public search engine’s final name. Windows Live Search and MSN Search were earlier Microsoft services, so they cannot be the answer to a question asking what replaced Live Search. Bing later became an important search provider for Yahoo as well.