You have to become allies with them. However, that's difficult and will make every other Empire war with you, so be sure it's worth it. well actually you cant even if u ally with them i can even prove it link[1]Read down up to the part where they say how to ally with them or go down to videos and you will see that there is no trade button even when allied...
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http://dbkwik.webdatacommons.org | 5 |