“Did you ever see the movie Casablanca?...same thing except no Nazis.”
—K's analogy of the Baltian's plight.
Baltian First Contact occurred on the night of Thursday, March 2nd, 1961 when a group of Baltian refugees landed on Earth just outside New York City. They came here on a mission to establish Earth as an apolitical neutral zone for aliens in need of a planet to relocate. This meeting became the cornerstone event in the formation of the Men in Black.
The MiB was formed in the mid-1950s as a poorly-funded branch of the US Government attempting to make contact with extraterrestrial life to which no one took seriously. That was until a group of Baltian visitors contacted the agency and coordinated a rendevous. There were 9 humans present at the landing: 7 MiB agents including Zed, Agent D and Alpha, one unnamed astronomer and a young man named Kevin Brown who got lost trying to visit his girlfriend.
Kevin had a bouquet of flowers originally intended for his significant other, but ultimately presented it to one of the Baltians as a welcoming gift. As a result of his newfound knowledge of what occurred that night, Kevin was recruited into the MiB, sadly leaving behind his girlfriend and personal life in the process.
The MiB agreed to fully assist the Baltians and it was decided to make Earth a residence for planet-less aliens along with the agency being able to protect Earth's citizens from any extraterrestrial threat. The agency knew Humans were too primative to fully coexist with alien life and thus implimented a protocol to disguise the appearence of an extraterrestrial if they wished to live on Earth.
Any of evidence of the landing or their existance was concealed so as not to cause hysteria among the civilian population though the landing was documented in an archival photo album. The Baltians came to Earth aboard spacecrafts that the MiB disguised as Observation Towers for the 1964 New York World's Fair.
As a token of gratitude, the Baltians helped developed an array of advanced technology for the MiB among which possibly included, the neuralyzer. Some of that technology was used to make various items to which the MiB holds the patents for, funding their operation. This alliance completely revamped the entire infrastructure of the MiB to the agency that it is today.
The MiB have since severed any connection with the US Government on the grounds that they were too intrusive. Not too long after, the Baltians left Earth for reasons not given and their current whereabouts remain undisclosed.
The animated series establishes that the Baltians and the MiB have maintained a good relationship since First Contact. They periodically return to Earth every 10 years or so to show their latest technological innovations though they only appear in the episode "The Head Trip Syndrome".
Baltians resemble the stereotypical "grey alien" often depicted in pop culture, inferring that they were the ones who inadvertantly created this iconic image.
There's minor speculation that the Baltian homeworld may have been ravaged or destroyed by Bugs. It seemed rather peculiar that Edgar knew how to operate and pilot a Baltian flying saucer towards the end of the first Men in Black film.