The manufacturing industry in Korea was a source of worry for many western guitar manufacturers in the late 1970s and early 1980s. The cheap replicas of Fender and Gibson's licensed designs threatened to take away their customer base. However, since the early 1990s many of the big-name brands have moved manufacturing operations for their entry-level guitars to Korea, taking advantage of the ever-improving quality of their instruments.
Tokai was originally a Japanese company that started building guitars in the late 1940s but later moved to Korea. The instruments that originate in Korea have a letter preface at the start of the serial number. Tokai began to produce highly accurate replicas of Gibson and Fender guitars in the 1970s, and the American firms sued Tokai in order to protect copyrights. Some of the Tokai models even included the original model names, such as the "ES145" and the "SG." The models produced in this period are referred to as "Lawsuit Guitars" and are highly sought after because of their unusual history. Ironically, Tokai's Korean factory now manufactures Gibson's budget Epiphone range.
Samick was originally a piano manufacturer in South Korea, with most of its products being sold domestically. With the rock and roll boom in the U.S., the company began to build low-priced guitars for export. By the 1970s Samick had improved the quality of its manufacturing techniques and released its own designs into the market under a variety of brand names. They produced many of the short-lived "shred" brands of the 1980s such as Charvel and Fernandes; in terms of sheer volume, Samick is the world's largest manufacturer of stringed instruments.
Squier is Fender's entry level brand. Introduced in the 1980s to counter the influx of far-eastern guitars threatening Fender's sales. Fender set up its own far-east manufacturing facility and started producing budget-level copies of its own instruments under the Squier marque. Though initially intended only to compete with the copies produced by Asian companies, Squier has grown into its own brand, spawning many unique models of its own and a signature series endorsed by popular artists.
Though Cort isn't a brand name that immediately jumps to mind when thinking of major manufacturers, the company is actually one of the biggest instrument builders in the world. Out of South Korea, it handles manufacturing for Ibanez, ESP and Schecter guitars.