The Kingdoms of Korea

Gojoseon 고조선 (Ancient Joseon/Ancient Chosun 2333 BC � 108 BC)
The first Korean Kingdom recorded in written history is GoJoseon, which according to legend was founded in 2333 BC by Dangun Wanggeom , a grandson of heaven. Gojoseon was roughly centered in the basins of the Liao and Taedong rivers, encompassing southern Manchuria and the northern portion of the Korean peninsula.

The food of Korea at this time was probably mostly prepared from game, foraged (wild) grains and fruits, and the harvest of very early cultivation, and more than likely there was no preservation of foods other than simple drying.

There is evidence of earthen pottery development during the period of 8,000 BCE to 1500 BCE, so it is reasonable to believe that early types of hard flat breads, and boiled dishes were likely to have been developed. Cooking was most likely done over open fire, hot coals, and heated stone.

Fishing may have been limited to freshwater streams, lakes, rivers, and close in coastal waters where people could harvest fish or other seafood trapped in tidal pools. Clams, crabs, and other coastal seafood probably provided a good portion of the diet of any peoples who lived near the sea.

Sometime around 1500 BCE to 1200 BCE, rice cultivation was introduced to Korea, probably from China through Manchuria. Both dry field cultivation, and paddy cultivation spread throughout the peninsula. Evidence also shows that millets, barley, and wheat cultivation began to spread from small village type agriculture to more widespread cultivation. Domestication of livestock is also attributed to this period, as is the rise of bronze age culture. 

As Gojoseon grew in power, influence, and territory, long range trade with other cultures began. Exotic materials and foodstuffs made their way into Korea. It is not a very large leap to assume that the expensive and rare foods, spices, and cookware were reserved for the ruling class, giving birth to the first forms of Royal Cuisine.

With more abundant food sources, advances in pottery, and the use of bronze cookware, Korean cooking methods began to advance. The ability to cook with oils, use of fermentation and salting of foods led to more complicated dishes.

Buyeo or Puyo, was probably the second ancient Korean kingdom, and spanned the teritory from today's Manchuria to the northern portion of the Korean peninsula, from around the 2nd century BC to 494. Initially a very militaristic state, conquest brought foods and cooking techniques from different regions into Buyeo and from there spread to the southern city states and federated tribes.
The area conrolled by Buyeo consisted of fertile plains and river valleys well suited to agriculture and livestock, and the common people provided foods and labor for the ruling elite. Trade was established with the Chinese Han Commandaries which brought new foods, spices, and food animals to Korea.

Jin 400BCE?? to 26AD??

The Jin Federation was an early Iron Age culture that most likely was a federation of smaller states located in the southern portion of the Korean peninsula. There is some archeological evidence that Jin had established trade with the Yaori people of Japan, so it is probable that foods were part of that trade.
With the spread of iron technology, advances in pottery made by the introduction of the potters wheel, and increasing use of kilns, more and better cooking vessels were available. As brass became more common, use of these began to filter down from the nobility to affluent families and clans.