History and specifics
In the 23rd century, Sarai was the sector's commercial shipping hub. Its transit station managed parking orbits for freighters within its crowded orbital airspace. Sarai facilitated the transshipping of all sorts of items, but not dilithium.
In 2270, The starship USS Enterprise visited Sarai in search of Harry Mudd's freighter Superstella, which was loaded with several kilotons of dilithium badly needed by Starfleet. Sarai officials confirmed that the Superstella had not been there, but while the Enterprise was in orbit, Mudd initiated a subspace auction. Spock traced Mudd's location to NGC 104 near Romulan space. (TOS - Mudd's Angels short story: "The Business, As Usual, During Altercations")