The Steranmio Alliance, collectively known as the Steranmio, was a conglomeration of planets joined together in one political entity.
The members of the Steranmio Alliance had the reputation of being warrior races who armed every and any ship in their defence force extensively, often while compromising other systems like escape pods and medical facilities. (Star Trek: The Cantabrian Expeditions: "Howl")
This caused the Pilmarians to suffer severe economic and political problems. A cold war between the two powers started, going so far as to damage members of the same race on either side of the zones between them.
As the cold war stewed, hatred between the two sides grew until, in 2374, the tensions exploded into open warfare. Thousands of refugees tried to flee to non-aligned worlds, but the war quickly spread. As the Hanej Gateway opened and the refugees flowed through, the war growing more intense and bloody, members from the Pilmarians, the Steranmio and non-aligned worlds sought the help of the United Federation of Planets to negotiate a peace. A Starfleet task force, led by the USS McCaffrey and accompanied by the USS Cantabrian-A and USS Prospect-A, arrived in late 2374 to assist in the process and keep the peace. (Star Trek: The Cantabrian Expeditions: "Said I Was Saved but You Never Said What From")
The Steranmio Alliance spanned nearly 1,200 light years and was approximately 7,000 light years from the Federation. Situated between the Steranmio and Federation was assumed to be Renai'i territory. Without the Hanej Gateway, a nearly instantaneous journey between the two areas, it would take an average starship seven years to get between the two areas at a high rate of warp. (Star Trek: The Cantabrian Expeditions: "Said I Was Saved but You Never Said What From")