Currently, little printed material exists in English about the history of Hai Dong Gumdo. There is comparatively little written in Korean about it either. What has been written in Korea is closed to me at this time. As I learn more I will share it here. I will offer simply information, not commentary which I am unqualified to present.

It appears that there has been some attempt made to trace the lineage of Haidong Gumdo back to the Kokuryo Kingdom, specifically mentioning King Kwang Kaeto (371-384 AD). Other figures, one named General Yu Yu and another, a monk referred to as Sulbong Sunim, are mentioned as playing significant roles in the orignial organization of this lineage of training. It is important to note that the name Haidong Gumdo is a modern device. You will not find reference to a martial art or system of training with this name in any history book. In one sense the name simply means Korean Swordsmanship. Korea was once thought of as the land of the East Sea. The characters for Hai and Dong carry several meanings. The general meanings are Sea and East. Haidong refers to Korea and along the southern tip of Korea is still in common use for place names. It has other shades of meaning, however, which are lost in translation. Dong means east. It can also refer to the rays of sunlight at dawn. Hai means sea. It also refers to the energy of the sun. Gum refers to swords - specifically long bladed ones. Do has a wide variety of meanings but they tend to revolve around the principle of "a way". 'Do' in this context includes concepts such as areas of study, principles of behaviour or paths of self-improvement but it is not limited to these meanings. It is perhaps best to keep multiple meanings in mind and not allow the experience of the art to be shaped by just one facet.
The name was designed to reflect the tradition of swordsmanship in Korea. It was also coined to bring to mind the image of the sun's first rays glinting from an upraised sword. Techniques and tactics change with time, contact with the enemy and advances in technology. The character of a people and how they train is more resistant to change and this is part of what the choice of name is trying to relate about Korean swordmanship. As swords have evolved over the centuries so too must the methods of employing them. Haidong Gumdo is striving to preserve the intangibles of Korean swordsmanship. The art employs one class of weapon and a practical corpus of techniques, using that material to provide students with a path to self-improvement and discovery.

I have been told that those trained under Sulbong Sunim became called after the place where they trained. This training hall is said to have been in the environs of Paekdu Mountain which lies on the present day borders of North Korea and China. As time passed the students became known as Samurang. The Samurang have been put forth by some as one of many possible influences on the social foundation of the Japanese Samurai. This is said because it is known that they adopted a code which included loyalty, filial piety, courtesy, justice, faithfulness, intelligence, virtue and physical fitness. It is also known that settlers from what is now Korea played a very significant role in the shaping of early Japanese culture. What is not known is whether that early contact by the Paekche Kingdom of Korea would have included any of these social elements from the Kokuryo Kingdom.
General Yu Yu is reported to have founded a school of swordsmanship called Jang Baek. I am told it was located in a mountain range by the same name.
I have little information about how the traditions and codes started with these groups in the 4th century were transmitted to the present day other than that they were shared 'man to man' and in such monastic arts as Kichun. Military manuals also play a role by preserving vocabulary and identifying the outside influences which helped shape Korean fighting arts. What I do know is the timeline of the formation of the Haidong Gumdo Federation we know today. Basic elements from that timeline are listed below. My thanks go to Lois Chang for her translation.