The 2370s decade covers the period from 2370-2379.
In this decade, the United Federation of Planets continued their exploration of the Gamma Quadrant by way of the Bajoran wormhole, discovered in 2369. By the end of 2370, the powers of the Alpha Quadrant had been forced into a cold war with the Dominion, a major political entity in the Gamma Quadrant, that would continue until 2373. This cold war would degenerate into open hostilities by the end of that year, and continue until 2375. The war turned out to be one of the bloodiest interstellar conflicts in galactic history, leaving the Klingon Empire set back by nearly a decade and over 800 million Cardassian civilians slaughtered at the hands of their former Dominion allies during the final battle of the conflict. (Star Trek: Deep Space Nine)
Hostilities with the Borg Collective was also a major concern throughout the decade. A second attempt to assimilate Earth in 2373 left Starfleet forces stretched relatively thin for months, a fact that was a source of concern when the Federation realized that the Dominion were planning to invade the Alpha Quadrant. (Star Trek: First Contact, DS9: "In Purgatory's Shadow")
Additionally, the Federation began its first exploration of the Delta Quadrant in 2371, when the USS Voyager was transported there by an entity called the Caretaker. In addition to collecting a multitude of data on the Delta Quadrant that would keep Federation scientists occupied for decades, Captain Kathryn Janeway and her crew made more first contacts with alien species since the era of James T. Kirk and the original USS Enterprise. On the final leg of their journey, the Voyager crew managed to deal near-catastrophic damage to the Borg Collective, however it remains unknown if the Borg were able to recover. (Star Trek: Voyager)
- First Contact between the Federation and the Dominion occurs in 2370 and results in the destruction of the USS Odyssey and a three year cold war between the two powers. (DS9: "The Jem'Hadar" – "Call to Arms")
- The Borg make a second attempt to assimilate the Federation in 2373, but are stopped by the crew of the new USS Enterprise-E. (Star Trek: First Contact)
- The Dominion War rages for two years between 2373 and 2375, resulting in the deaths of hundreds of millions of people before a decisive Federation Alliance victory. The war devastates the Alpha Quadrant, especially the Cardassian Union. (DS9: "Call to Arms" – "What You Leave Behind")
- The USS Voyager journeys through the unexplored Delta Quadrant between 2371 and 2378. During Voyager's final push to get home, the vessel's crew manages to do massive damage to the Borg Collective and their transwarp network. (Star Trek: Voyager)
- The entire Romulan Senate is assassinated by Shinzon in 2379, whose attempt to destroy all life on Earth is thwarted by the crew of the Enterprise-E. Following these events, the Romulans become "interested in talking" with the Federation. (Star Trek Nemesis)
This decade covers a vast majority of the Star Trek canon, as the final season of Star Trek: The Next Generation, the latter six seasons of Star Trek: Deep Space Nine, the entire run of Star Trek: Voyager, the four Next Generation movies, and the final episode of Star Trek: Enterprise, "These Are the Voyages..." all take place in the 2370s.