Complex sentence: The Northern Eagles were a short-lived rugby league team, formed during the rationalisation of the National Rugby League (NRL) by the merger of the Manly-Warringah Sea Eagles and the North Sydney Bears, in 2000.
Split into simpler sentences: The Northern Eagles were a short-lived rugby league team, that competed in the National Rugby League (NRL). The club was formed during the rationalisation process of the NRL by the merger of the North Sydney Bears and the Manly-Warringah Sea Eagles in 2000.