Nokia's Symbian phones are often seen as the big victim of the Nokia-Microsoft alliance, but the truth is that the old OS was dying already. There was a promising new OS on the horizon poised to replace it, unfortunately it powered only one phone in its short existence - Nokia N9. Development of Symbian and Linux-based OSes was scrapped so that the company could focus on its upcoming Lumia line (powered by Microsoft's Windows Phone OS). This was quite unexpected as MeeGo, N9's operating system, had two giants backing it. The family tree is complicated, but the simple way to describe it...
Source: https://www.gsmarena.com/flashback_nokia_n9-news-40454.php
