Spoiler warning: Plot and/or ending details follow.
Society and culture
Pakleds were noted for their apparently underdeveloped verbal communication skills. However, they used this, as well as their simple-looking appearance, to deceive other races. They controlled an area of space that included the Kalla system. However, they appeared to be a largely nomadic culture, traveling between worlds in search of supplies and materials needed for their continued survival. (TNG episode: "Firstborn")
First contact between the Federation and Pakleds took place in the year 2365, when the USS Enterprise-D answered a distress signal from a Pakled transport, the Mondor. After effecting repairs to their ship, the Pakleds attempted to hold Enterprise chief engineer Geordi La Forge captive, but eventually released him after witnessing a demonstration by the Enterprise. (TNG episode: "Samaritan Snare")
In late 2373, a Borg cube on a direct course for Sector 001 encountered the Mondor en route. The Borg Collective deemed the Pakleds unintelligent and considered it an inefficient use of resources to assimilate the freighter. However, they were later assimilated when the Borg needed extra reinforcements in their battle with Starfleet forces in Earth orbit. (TNG - Strange New Worlds 10 short story: "A Dish Served Cold")
There was a strong Pakled presence on Deep Space 9 in the 2370s decade. They would often frequent Quark's, the Klingon restaurant, and other establishments on the Promenade. (DS9 episodes: "The Collaborator", "Bar Association")
By 2380, the Pakleds, constantly underestimated by the galaxy, had salvaged technology from over thirty different species, including the Dominion and the Borg, to the point that Mondor-class vessels could readily overpower a California-class ship. The USS Cerritos was nearly destroyed by several Pakled ships before they were saved by the USS Titan. Reflecting on these events, Captain Carol Freeman and Ensign Beckett Mariner believed that the Pakleds had been allowed to advance so much due to Starfleet's failure to keep a constant watch on potentially dangerous species. (LD episode: "No Small Parts")