Arthur and the others had reached the lower region, all areas were vegetated land and farmland.

Arthur could see over four hundred fields, but there were no farmers in this area. It seemed the farmers had believed that their land was barren.

Looking east from the farmland, Arthur was surprised to see three castle areas.

He then looked to the west from the farmland and there were two castle areas there. He turned to Luca and his group.

"Why did the nobles leave the upper realms to build their castles here? Don't you think that's very strange?"

"Yes, Your Majesty," said Luca, and the others nodded.

"My king, there is a possibility that they found something valuable in this lower region and decided to stay here." said a shy knight.

The knight had blond hair and dark brown eyes. If he were on earth he would look like a K-pop artist. He had no muscles and looked weak, like a twig. Arthur is not worried because once he started training them, they will have a lot of muscles.

The knight's voice shows nervousness and fear. It was clear that he lacked any confidence in himself.

"What's your name, age, rank, and Captain?", Arthur asked.

"Reinhart Gramm, age 17, Sergeant, under Captain Marco. Your Majesty."

"Reinhart, that was an excellent suggestion. They might be things there that could help us better the kingdom. Excellent." Arthur said while smiling.

Arthur was shocked that Reinhart was 17 years old. He looked like a 14-year-old boy.

Reinhart was excited to be complimented by the king. They know that when he spoke he was shaking like a leaf. Seeing His Majesty in high spirits, he felt more confident.

The other knights also nodded and thought that what Reinhart said made sense. After all, even the citizens didn't stay here. So, why did the nobles have to build castles here? Everything this is very suspicious and needs to be questioned.

"Let's go east first. I want to know why they need more castles there, compared to the west."

The first castle area they entered was located on a hill. When they entered the castle area, Arthur was surprised by what he saw.

There was a group of monsters that looked like lions looking for their way out of the castle.

Altria beat the lions without hesitation, and the lions became very frightened and tame. Only the Lion King refused to surrender and was killed by Altria.

Inside the castle, Arthur carefully observed the whole situation of the castle. The castle looked so messy, he could see various cutlery on the floor.

Looking further you can see women's shoes and dresses in the middle of the stairs, torn paintings on flower vases, and above the dining table, there is some rotting food.

"Is the King's wrath so frightening? So they will throw away their food?" Arthur asked. They were just silent. They couldn't answer Arthur's question. They also feel very dizzy.

'What's going on here?' They thought.

In another courtyard, they saw a large number of ashes scattered all over the floor. Chaotic footprints and swords with bloodstains can also be seen here.

They started searching every house in the castle area but couldn't find anything of value. As they were about to leave, Arthur saw a cave behind the castle.

Once they reached the cave entrance, They immediately put their hands on their swords to prepare for the sudden battle.

Seeing that nothing happened in front of the cave door. when Arthur would enter the cave but is immediately stopped by Luca.

Seeing that nothing happened in front of the cave entrance. Arthur who was about to enter the cave was immediately stopped by Luca.

"Leave the inspection of this mine to us, Your Majesty," Luca said.

"Hmm... Alright..." Arthur nodded.

"Captain Jonathan, Captain Marco, you guys lead some knights to inspect the cave." Luca gave the order.

"Yes, Marshall," answer both

Jonathan and Marco lead his team into the cave. Soon they came out of the cave and brought three stones.

Arthur knew the names of these three stones. The red stone is bauxite, this stone is similar to Bauxite, found at Les Baux in southern France. The stone with a light yellow color is Trona. The white stone is Feldspar.

After confirming the safety and the stones they brought. Arthur immediately went into the cave to see if there were any other stones and metals.

The cave had Bauxite, Trona, and Feldspar stone on the walls and ceilings.

People used Bauxite, Trona, and Feldspar as decorative stones on the continent. In their eyes, these three were just ordinary stones. Completely worthless.

But to Arthur who came from the earth, they were priceless. Bauxite raw material for aluminum, aircraft, and household appliances.

The manufacture of Aluminum occurs in two stages:

The Bayer process is a bauxite ore refining process to obtain aluminum oxide (alumina), and

The Hall-Heroult process is a process for smelting aluminum oxide to produce pure aluminum.

Trona could be used in glass making, paper, detergents, textiles, etc.

Feldspar is a raw material for making ceramics, glass, etc.

This was truly a huge win for them.

The cave was so big that Arthur thought they would easily get lost if they kept going forward. So they decided to leave. When Arthur turned around he didn't glance at the end of the cave passage and saw a stone that had something like metal in it.

Arthur took the stone. His eyes immediately shine.

"This... is this a Molybdenum stone?" Arthur said in surprise.

"Is Molybdenum stone useful, Your Majesty?" Luca asked curiously.

"Yes, it's Molybdenum, Molybdenite. Molybdenite was used to increase the corrosion resistance of swords, armor, and any silvery objects. This was the era of swords. Thousands of swords were forged daily in this world. It was for sure a treasure." Arthur explained to them.

"How do you know, Your Majesty?" Luca asked.

"You know my last weapon 'Zerstorer'. I made it by combining several ores, and molybdenite is one of them."

Although Old Arthur didn't know the names of the ores. He continued to experiment to make weapons. The result was the last weapon he wielded with the strongest durability under magic weapons.

"Zerstorer seems to have been taken by son Marshal Zinga, the first prince's loyal subordinate."

"Let him hold it for a while. Okay, let's go to the next castle area."