(covers information from several alternate timelines)
The 2390s decade covers the period from 2390-2399.
- A new variant of the Starfleet uniform is introduced. (PIC: "Remembrance")
- 2395: According to the imager at the Velara Base, this year is when Velara III would have become a class M planet suitable for colonization. However, the project was discontinued with the discovery of the microbrain in 2364. (TNG: "Home Soil")
- Because of the ban on synthetics, Thaddeus Troi-Riker is unable to be treated for mendaxic neurosclerosis and passes away. (PIC: "Nepenthe")
- In 2367, Lwaxana Troi estimates that Kaelon II would be destroyed or sterilized by its dying sun in thirty or forty years. (TNG: "Half a Life")
Consistent throughout all timelines:
- 2390: Chakotay, with the assistance of Harry Kim, Tessa Omond, and The Doctor (after being reactivated) changes the timeline so that Voyager doesn't crash on the Class L planet.
- 2391: Jake Sisko begins to study subspace mechanics and was awarded with a Betar Prize for his Collected Stories.
- 2392: The Doctor invents a synaptic transceiver for a neural interface.
- 2394: Voyager returns to Earth after 23 years in the Delta Quadrant. Chakotay dies in the same year.
The Path to 2409 lists events leading up to Star Trek Online during this time. Star Trek Online was initially intended to be set in 2399, but after development of the game was given to Cryptic Studios the setting was moved to 2409.
- 2393: Bajor gains full Federation membership.
- 2399: The Khitomer Accords dissolve. (Star Trek Online)