Only certain aliens are canonical at this point. The Gorn are not encountered for another decade. That is firmly established. The Borg are just over-used and badly watered down as an enemy.
The Cardassians and Breen however have no first contact date, and there was one Cardassian exile already living on Vulcan before this time, and the Klingons had already fought a war with the Breen.
As another poster said - this was the political situation in DSC:
The United Federation of Planets - Leading a galactic scientific and cultural renaissance, it was established 100 years ago. It is a young, confident and vigorous superpower. Involved in a Cold War with the Klingon Empire.
The Klingon Empire - In a state of Cold War with the United Federation of Planets. It is currently plowing resources into science and the military. It possibly experienced a militaristic cultural revolution after the 2160s.
The Romulan Star Empire - In a state of self-imposed isolation similar to Tokugawa era Japan, following the devastating Earth-Romulan War. Any contact with the Federation is conducted via stealth reconnaissance probes.
The Cardassian Union - The Cardassian Central Command is attempting to lead the Cardassian people out of poverty through a patriarchal statist cultural revolution. The Cardassian people still suffer famines.
The Breen Confedracy - Opportunistic, mercenary and piratical, they have fought conflicts with the Klingon Empire, but are relatively isolated. Unpredictable and aggressive. Known for using captured crews for slave labour.
The Tholian Assembly - Isolationist, like the Romulans, but with no expansionist desires. They are extremely aggressive regarding alien expansion near their space, and will attack others pre-emptively to prevent this.
The Orion Colonies - In a variable friendly/antagonistic relationship with the Federation and Klingons. Home to pirates and criminals. Some colonies political elites are controlled by the Orion Syndicate criminal organization.
The Gorn Hegemony - UNCONTACTED [First contact in 2267 - James T Kirk]
The Ferengi Alliance - UNCONTACTED [First contact in 2364 - Jean-Luc Picard]