北方女真族所建的金国崛起，宋室为了收复燕云诸州，便联金灭辽，但其弱点也为金国所洞悉。
To recover the sixteen states of Youyun , the Northern Song sent an emissary to the state of Jin to negotiate an agreement for a joint attack on the Liao . However , the resort also exposed its weakness to Jin .
联金灭辽