The four great inventions of ancient China, papermaking, printing, compass, and gunpowder, the first two are available, and the latter two must be taken out, the compass can make people not lose their way, and the precondition for the compass is that the compass can be mined, and the research and development of gunpowder is a little dangerous, and the technology itself is not too difficult.

Su Yan wrote down the compass and gunpowder, and after thinking about it for a while, Su Yan wrote "glass" after these two items.

There's a story:

More than 3,000 years ago, a European Phoenician merchant ship, laden with the crystalline mineral "natural soda", sailed on the Belus River on the Mediterranean coast.

As the tide went down and the merchant ship ran aground, the crew went to the beach, some of them brought cauldrons, firewood, and a few pieces of "natural soda" as a support for the cauldron to cook on the beach.

After the crew finished eating, the tide began to rise, and they were about to pack up and board the ship to continue sailing, when suddenly someone shouted: "Come and see, everyone, there is something bright and sparkling on the sand under the pot!" ”

The crew brought the glittering things to the ship to study them carefully, and they found that there was some quartz sand and melted natural soda stuck to them.

It turned out that these glittering things were the natural soda that they used to make the pot stand when cooking, and under the action of the flame, the substance produced by chemical reaction with the quartz sand on the beach, this is the earliest glass, and later the Phoenicians mixed quartz sand with natural soda, and then melted it with a special furnace to make glass balls, which made the Phoenicians make a fortune.

I don't know if the story is true, but it is enough to show that it is not too difficult to make glass, and there are many uses for glass, such as installing glass on doors and windows to increase the brightness of the interior, fine glass products for trading, building glass for roof greenhouses, growing vegetables in winter, and even using glass to make telescopes.

Of course, the initial stage of glass technology could not reach the level that Su Yan wanted, and it still took time to study before the results could be taken out, and these things did not delay Su Yan from including "glass technology" in the science and technology chapter of the "First Five-Year Development Plan of Xia Kingdom".

Shipbuilding, ironmaking, compass, gunpowder, glass, hydraulic machine tools...... Write down one technology after another, and there may be many technologies that can be included in the "First Five-Year Development Plan of Xia Kingdom", waiting for Su Yan to think of and add them.

After the science and technology chapter is the territory, Su Yan temporarily put the territory and trade together, after all, the ships of the Xia Kingdom can only sail in the Yellow River Valley for the time being, and Su Yan also regards the Yellow River Valley as the territory of the Xia Kingdom.

The territory of the Xia Kingdom is calculated according to the farthest cities in the four directions of the Xia Kingdom, east, west, north and south, and the interior is the territory of the Xia Kingdom.

Originally, Su Yan planned to use the strategy of "encroachment step by step", starting from the area where the Xia Kingdom is currently located, building a city along the main trunk of the Yellow River to the east and west, building a city at intervals, advancing step by step, and finally occupying the entire Yellow River Basin.

However, when Su Yan wrote the "First Five-Year Development Plan of the Xia Kingdom", he found that the strategy of "encroachment step by step" was a bit slow, and it was completely possible to be radical and build new cities in areas far away from the Xia Kingdom.

For example, the coal needed for iron smelting has been found in the Yan clan's hometown, and if you want to collect coal mines, it is best to establish a settlement in the Yan clan's hometown, arrange slaves to dig coal mines, and also arrange warriors to guard the slaves.

The work of digging copper, iron, and coal mines is very heavy, and it is not good for the health of the miners, and this kind of labor has been replaced by slaves, and the citizens of Xia only serve as caretakers.

Su Yan originally believed that a settlement could not accommodate many people, too few people could be defeated by the enemy, far from the mainland could not get support, even if a city was built, it could be besieged by the enemy.

This is what Su Yan thought about before, a city with a population of about 10,000, no matter how strong the enemy is, it is difficult to break through the city of Xia with a population of 10,000.

What's more, now Su Yan has no intention of building only one city in the area of the Yan clan's hometown, the Yan clan's hometown is on the south bank of the Yellow River, and the north bank is the grassland, and the nomadic tribes on the grassland have always been the main source of cattle and horses in the Xia Kingdom, and the Xia Kingdom needs more cattle and horses.

It is better to build a city on the border of the grassland, open up pastures on the grassland, graze cattle, horses and sheep in large quantities, and formally establish cavalry troops, so that the iron cavalry of the Xia Kingdom can crisscross the grassland and seize cattle, horses and sheep from those nomadic tribes, so that the Xia Kingdom will not lack cattle and horses.

The distance between the two cities is not too far, and it is about a day's journey by boat, if you take a boat from the south bank of the Yellow River to the north bank of the Yellow River, and then ride a horse to another city, the time can be shortened to one-third or even shorter.

The two cities support each other, and they can gain a foothold in this area, even a city with a population of 10,000 can also gain a foothold, and in the future, they can also build a few more cities according to the situation in the region, anyway, sooner or later, the cities of the Xia Kingdom will be all over the Yellow River Valley.

The only problem is that the city is far away from the Xia country, and it takes ten days to half a month to communicate between the two places, and the distance is too far, which may cause people who have joined the Xia country for a short time to have other thoughts, so when building a new city far away from the Xia country's native area, it is best to move the family that has joined the Xia country for more than ten years, and it is best not to serve as a city lord for more than five years.

Wherever there are necessary products of the Xia Kingdom, cities can be established in this area, and by the way, the territory of the Xia Kingdom is also increasing wildly.

Su Yan regarded the entire Yellow River Valley as the territory of the Xia Kingdom, but it would take time to really occupy the entire Yellow River Basin, and this time was mainly spent on dealing with other tribes in the Yellow River Basin.

At this time, the Xia Kingdom can follow the plan in the population chapter of the "First Five-Year Development Plan of the Xia Kingdom", first contact more tribes in the name of trading, on the one hand, trade with them some of the products that the Xia Kingdom needs, on the other hand, preach to them and spread the strength of the Xia Kingdom, and even attract some tribes to join the Xia Kingdom.

When the Xia Kingdom expanded to a farther area, those tribes did not choose to join the Xia Kingdom, nor did they move away from the Yellow River Valley, and the only thing that awaited them was war.

Slaves are not as important as the citizens of Xia Kingdom, but slaves still have some roles, such as heavy and dangerous work such as mining, all dangerous work can be handed over to slaves, slaves are not nationals, and they are not very distressed when they die.

[Let's talk about what other technologies can be taken out in terms of science and technology, and Heng Yi thinks of the pain in the brain] ()

Please remember that the first domain name of this book is:.