Question: What submachine gun was used before the L85A1 assault rifle and during the Korean war?

Context paragraphs:
Daewoo Precision Industries K1: The Daewoo Precision Industries K1/K1A is a South Korean carbine assault rifle, the first modern firearm developed by Agency for Defense Development (ADD) and manufactured by Daewoo Precision Industries, and entered service in the Republic of Korea Armed Forces in 1981.  Although the K1 uses .223 Remington, it is classified as a submachine gun by the South Korean military and the current manufacturer S&T Motiv, because the K1 was intended to replace the M3 submachine gun.

Daewoo Precision Industries K3: The Daewoo Precision Industries K3 is a South Korean light machine-gun.  It is the third indigenous firearm developed in South Korea by the Agency for Defense Development, following the Daewoo Precision Industries K1 submachine gun and Daewoo Precision Industries K2 assault rifle.  It is manufactured by Daewoo Precision Industries, current S&T Motiv.  The K3 is capable of firing both 5.56×45mm NATO and .223 Remington rounds like the K2 assault rifle.  The K3 light machine gun entered service since 1989, replacing M60 machine gun from frontline use.

Sten: The STEN (or Sten gun) was a family of British submachine guns chambered in 9×19mm and used extensively by British and Commonwealth forces throughout World War II and the Korean War.  They were notable for having a simple design and very low production cost, making them effective insurgency weapons for resistance groups.

Desert Tech SRS: The Desert Tech Stealth Recon Scout (SRS) is a bolt-action sniper rifle developed by the American firearm manufacturer Desert Tech (formerly Desert Tactical Arms).  It was unveiled at the 2008 SHOT Show.  It is known for its bullpup design, which lets the rifle have a similar barrel length to other rifles while remaining as compact as an assault rifle or submachine gun.  The gun is also lightweight, weighing 10.5 lbs at its lightest, which makes it easy to use with a bipod or large scope.

Beretta M1918: The Beretta Model 1918 was a submachine gun that entered service in 1918 with the Italian armed forces.  Designed initially as a semi-automatic rifle, the weapon came with an overhead inserted magazine, an unconventional design based on the simplicity of allowing a spent round to be replaced using only gravity.  The gun was made from half of a Villar-Perosa aircraft submachine gun, and as such it can be considered the first submachine gun issued to and used by the Italian armed forces, and is possibly the first SMG used as a general-issue combat weapon.

Arsenal submachine gun: The Arsenal M23 submachine gun (Estonian: "Arsenali püstolkuulipilduja" ) (also known as Arsenal Tallinn) was an Estonian submachine gun from 1926 through 1935.  These submachine guns were designed and produced in the Estonian military equipment factory "Arsenal" in Karjamaa, Tallinn, but production was not more than 600 units.  The weapon was chambered for the 9x20 mm semi-rimmed Browning cartridge to be compatible with ammunition for the Browning FN M1903 pistol which had been adopted by the Estonian Army.  It operated on the blowback system and was essentially similar to the MP18.1; having a wooden stock, slotted barrel jacket, and horizontal left side magazine feed.  A uniquely slender 40 round single column box magazine led to frequent cartridge feeding problems; and cooling fins which were machined lengthwise along the barrel to promote cooling air flow when firing (similar to the Lewis machine gun), unnecessarily complicated production.  It was used by the combat support units of the Border Guard, the Estonian Defence League and the Estonian Defence Forces.  The Arsenal submachine gun was replaced in Estonian service by the Finnish Suomi KP/-31 submachine gun in 1938.  The Estonian Army sold a few samples to Latvia and all of the remainder found their way to Republican forces during the Civil War in Spain.

Vz. 58: The VZ.  58 ("model 58") is a 7.62×39mm assault rifle designed and manufactured in Czechoslovakia and accepted into service in the late 1950s as the "7,62 mm samopal vzor 58" ("7.62mm submachine gun model 1958"), replacing the vz.  52 self-loading rifle and the 7.62×25mm Tokarev Sa 24 and Sa 26 submachine guns.

M2 Hyde: The Hyde-Inland M2 was a United States submachine gun design submitted for trials at Aberdeen Proving Ground in February, 1941.  Work was undertaken by General Motors Inland Manufacturing Division to develop workable prototypes of George Hyde's design patented in 1935.  The model first submitted for trials in April 1942 was designated the "Hyde-Inland 1".  Trials revealed the design was superior to the M1 submachine gun in mud and dirt tests, and its accuracy in full-automatic firing was better than any other submachine gun tested at the time.  An improved "Hyde-Inland 2" was designated U.S. Submachine gun, Caliber .45, M2 as a substitute standard for the M1 Thompson in April, 1942.  As Inland's manufacturing capacity became focused on M1 carbine production, the US Army contracted M2 production to Marlin Firearms in July, 1942.  Marlin began production in May 1943.  Marlin's production failed to match the trials prototype performance; and Marlin's original contract for 164,450 M2s was canceled in 1943 upon adoption of the M3 submachine gun.  The M2 is chambered for the .45 ACP cartridge and used the same 20- or 30-round magazine as the Thompson.  Its cyclic rate of fire is 570 rounds per minute.  None of the approximately 400 manufactured were issued by any branches of the United States military.

Sterling submachine gun: The Sterling submachine gun is a British submachine gun.  It was tested with the British Army in 1944–1945 as a replacement for the Sten but it did not start to replace it until 1953.  It remained in use until 1994, when it was phased out as the L85A1 assault rifle was phased in.

Sterling SAR-87: The Sterling SAR-87 is a military assault rifle of the late Twentieth century.  The Sterling Assault Rifle (SAR), which included elements from Sterling's earlier Light Automatic Rifle (LAR) design, was jointly engineered by Sterling Armaments Company and Chartered Industries of Singapore in the early 1980s as an advanced version of the AR-18 for the export sales.  It was also offered to the British Armed Forces, who declined it because they were already in the process of adopting the SA80 bullpup design manufactured by Royal Ordnance Factories.  The SAR-87 was a robust weapon based on the well tried AR-18 with the versatility of the M16 rifle.  It could also be converted from 5.56×45mm NATO to 9×19mm Parabellum by changing the barrel and bolt assembly, to provide a submachine gun for Police forces.  Sterling Armaments tried to push the rifle, renamed SAR-87, for some more years, but at the end of the 1980s, it was bought out by British Aerospace/Royal Ordnance and closed.  Less than 100 SAR-87 rifles were manufactured.

Supporting paragraphs: Sterling submachine gun Sten
Answer: Sten