The Treaty of Wolf 359 was a diplomatic treaty made between the Federation and the Borg in the alternate future of 2400 during the War of the Prophets.

The treaty was made with the assistance of Admiral Seven of Nine and Hugh. The treaty resulted in the two participants becoming allies with technological exchanges taking place. Nanite based medical surgery was traded with the Borg who shared the technological secrets of Transwarp technology.

(DS9 novel: Millennium The War of the Prophets)

Its not been stated whether this is a reformed Borg Collective or a group of rogue Borg like the Independent Nation of Borg.