Alshain IV was the inhabited fourth planet in its star system. This class M world had an oxygen-nitrogen atmosphere and a forested surface environment with large rock formations floating in the air. It was the homeworld of the Alshain, a technologically advanced humanoid civilization that lived in close association with a native butterfly species that enabled them to fly.
In the late 29th century, the magnetic poles of Alshain IV began to shift; over the next three centuries, they moved fourteen degrees west of where they had been for hundreds of thousands of years. As the Alshain relied upon the planet's magnetic field to navigate during flight, they constructed an orbital array of geomagnetic compensator satellites to adjust for the shift. However, after the Burn in the 31st century, the Alshain ran out of dilithium and could no longer keep the satellites powered.
In 3190, the USS Discovery jumped to Alshain IV to renew relations between the Alshain and the Federation. Despite a brief misunderstanding, Captain Michael Burnham and Cleveland Booker successfully completed their mission after restoring the Alshain satellite array. (DIS: "Kobayashi Maru")
In the real world, Alshain is the traditional name of the Beta Aquilae star system (and as of 2016 the official name of Beta Aquilae A, the system's primary star), but while Beta Aquilae II is mentioned in TNG: "Eye of the Beholder", the two names have not been connected in Star Trek canon.
According to Star Trek: Star Charts ("United Federation of Planets I") and Stellar Cartography: The Starfleet Reference Library ("Federation Historical Highlights, 2161-2385"), the Beta Aquilae (Alshain) system was located in the Alpha Quadrant. It was a binary star system consisting of a Class G star and a Class M star.