Harald Blatan, the King of Denmark (reigned 940-986), conquered the entire country of Denmark and Norway and made the Danes Christians. The achievements of Harald Blatan, as recorded on the Yellowstone, are commemorated by the order of King Harald to commemorate his father Gaum and mother Trela.

Although nearly a thousand years have passed, contemporary Europeans inevitably shudder at the mention of the "terrifying Viking era". Thinking back to that day, the Norman (other countries refer to Vikings as Nordic) pirates rode the wind and waves, dominating wherever they went, what a majestic presence it was. There was an emperor who pushed the career of Norman pirates to its peak, but it was also him who played a significant role in the cessation of pirate war drums. He was the proud Harald Bluetooth King of Denmark.
Harald is known as the Bluetooth King because Blatan translates to Bluetooth in English. However, historians believe that during the Viking era, the word Black and often referred to Black, so a more accurate translation would be Blacktooth. The saying that one eats too many blueberries and has a blue tooth should be a supporting statement.
Harald is the son of King Gome. The era of King Gaum and King Harald Bluetooth was the formation of the Danish state. In the central part of the Jutland Peninsula in Denmark, there is a small city called Yelin. There are two stones at the entrance of the church in Yelin, one large and one small. The large stone features a Christ statue with a halo around its head and Old Northern Irving. This is the tombstone erected by Harald on the grave of his parents. The Danes refer to these two stones as the "Yellowstone" and see them as proof of the birth of the Kingdom of Denmark. During the reign of King Gaum, in order to resist the invasion of the southern Wendy and Saxon peoples, under the leadership of Queen Trela, the Danes built a "Danaviok Line" in the southern part of the Jutland Peninsula. After the succession of the Bluetooth King, Schleswig and the surrounding islands of the Jutland Peninsula were incorporated into the Danish territory, and the unified Kingdom of Denmark was officially formed. In 961, he took advantage of the internal turmoil in Norway and sent troops to invade Norway, defeating and killing King Haakon of Norway, forcing Norway to submit and laying the foundation for the future thousand year alliance between Denmark and Norway. During his reign, he intervened in the issue of succession to the throne of the Duchy of Normandy in France and was a promoter of the piracy industry.
As early as the 4th and 5th centuries AD, the Norse people began to operate in various parts of Europe, mainly engaged in trade and sometimes settled there. But starting from the late 8th century, the activities of the North gradually turned into large-scale and destructive pirate activities, possibly due to population pressure and class division in the late primitive society, deepening social conflicts. Their wooden boats have fast speed and shallow draft, making it easy to head up the river from Haikou and deep inland. The Danes mainly attacked France and England, the Norwegians attacked Scotland, Ireland, and other places, while the Swedes developed towards Eastern Europe, and later established the Lurik dynasty in Ross. Wherever they went, they burned, killed, looted, and sometimes demanded ransom. The wealthy monastery was their main target of attack.

During the Bluetooth King era, neighboring Germany was gaining strength and launching an attack on Denmark. Bluetooth King was defeated by German Emperor Otto in the war and converted to Christianity. Bluetooth King may have persecuted Panatok multiple times due to jealousy, almost killing him, causing strong dissatisfaction from Svan. The conflict between father and son finally escalated to a point where water and fire could not tolerate each other. In the end, the father and son each fought in a duel at sea, and the elderly Bluetooth King could not defeat his son Svan. He had to flee into the forest and was ultimately shot dead by Parnatok in the forest.

Odin faith
Although Harald's Bluetooth King's proposal to slow down expansion was not realized, his reign brought about another significant change in Denmark, which indeed led to the end of the pirate era. This is the introduction of Christianity. This also starts with Denmark's original religion - the Odin faith.
In Norse mythology, the supreme god of war, Odin, resides in the Hall of Val. It is said that any warrior who bravely fights in war can ascend to heaven after death and become a guest of Odin. They can live with Odin in the Hall of Val and enjoy a beautiful life forever. Therefore, the Normans were incredibly brave and fearless in battle, which was closely related to their worship of Odin (and of course, to the harsh living environment in Northern Europe). Later on, Western Europeans who suffered from the invasion of the Normans realized that the fundamental way to subdue the Nordic pirates was to change their Odin faith and spread Christianity to them.
Christian faith
At the beginning of the 9th century, missionary Ansgar actively spread Christianity to Denmark and was known as the "founder of Nordic missionary work". However, until the reign of King Bluetooth, Christians remained in the minority within Denmark. A bishop named Popo strongly urged Bluetooth King to convert to Christianity. It is said that he told Bluetooth King that he could use a piece of burnt iron to prove the power of God. Bluetooth King ordered people to put a piece of burnt iron in his hand, and after a period of time, Bishop Popo's hand was not injured. Bluetooth King was intimidated by the power of God and converted to Christianity, accepting the baptism of Christianity. His large number of subjects also converted to Christianity with him, which replaced the Odin faith and gained mainstream status in Denmark.
Profound impact
After the Nordic people converted to Christianity, their national identity underwent profound changes, gradually shedding the fishy smell of pirates. In contemporary times, they have become the group with the highest average cultural literacy in the world.
Unify Denmark, submit to Norway, and more importantly, introduce Christianity, gradually ending the pirate era. Harald Bluetooth should undoubtedly occupy a place in the world's influential imperial ranks.

For Nordic pirates, the lifestyle of siege and looting may be satisfying, but it is not beneficial for their long-term development. Instead, due to the massive loss of strong labor, they are in crisis. Harald Bluetooth King had a wise understanding of this and brought the pirate era to an end by introducing Christianity and other means. At the end of the pirate era, it was the time when the Nordic people truly and stably shared the fruits of the overall development of Europe.
When it comes to King Harald, few people know who he is. But when it comes to the famous Bluetooth technology, it can be said that everyone knows it, and the name Bluetooth technology comes from King Harald: he spoke eloquently and was good at communication. In his lifetime, he unified Norway, Sweden, and Denmark, just like the original intention of establishing Bluetooth