They were leagued together by a treaty.是什么意思？

They were leagued together by a treaty.

他们根据默契联合了起来.

they

pron. 他/她/它们，人们，大家，政府，当局，她们；

例句
The storms had abated by the time they rounded Cape Horn.
他们绕过合恩角时，暴风雨已经减弱。

were

be的过去时复数和第二人称单数形式，有时代替 was,用于条件从句、动词 wish 之后等；

例句
Shops, houses, and vehicles were set ablaze.
店铺、房子和车辆全都陷于火海。

leagued

v. 联盟( league的过去式和过去分词 )，等级，（运动）俱乐部的联合会，里格（长度单位，约等于 3 英里）；

例句
They were leagued together by a treaty.
他们根据默契联合了起来.

together

adv. 同时，在一起，一致地，不间断地；adj. 稳定可靠的，做事有效率的；

例句
We have to get our act together — we have to organize ourselves.
我们必须把劲儿往一处使——我们得组织起来。

by

prep. 在…旁边，表示方式，由于，经过；adv. 经过，表示保留或保存时用，短暂拜访；

例句
...expensive make-up that we saw being advertised by a beautiful model...
我们所见的由一位漂亮模特代言的昂贵化妆品

treaty

n. 条约，协议，协商，谈判；

例句
Delegates signed a treaty to reduce the armouries of conventional weapons in Europe.
各代表签署了协议以减少欧洲的常规武器装备。