On the grassland, Li Jing, Li Ji, and Hou Junji led the Tang cavalry to fight vertically and horizontally. Cheng Yanjin also led the army to cooperate with Wei Xiaojie's 40,000 foot soldiers to take the Liang State, and the Liang division was beheaded by his younger brother and sacrificed to the city to beg.

Wei Chigong completely took down the puppet Sui and captured Yang Zhengdao alive, and the entire Northern Expedition army can be said to have made great contributions. But Li Jing didn't feel much credit at all, and even felt shame.

Just because at the very beginning, the Tang army was surrounded by grassland people, like catching turtles in an urn, which made this Tang military god feel ashamed. He wants to wash away this shame with all the tribes of the steppe.

Therefore, all the areas where the Tang army passed were directly destroyed, and the young and strong were strangled, leaving the old and weak. snatched the cattle and sheep seats, swept all the way, and came straight to the Turkic king's tent.

At this time, Chang'an has undergone great changes, and the biggest change is that all the roads in Chang'an City have been replaced by cement roads, and even began to expand to the surrounding states and counties.

Cement kilns are everywhere in the entire Guanzhong Plain, and Li Er did not hide the formula of cement, but directly promoted it. It's just that every kiln that fires cement needs to be registered, and then a uniform fee is charged.

The price of cement on the market is also uniform, which prompts many small cement kilns to have to merge and operate, after all, the more the cement is burned each time, the lower the cost.

Gradually, the cement firing of the Tang Dynasty was controlled between the family and the Xungui family, the family controlled mostly the raw materials, and the Xungui was responsible for the production process. With the assistance of the ministers of the DPRK and China, Li Er gradually explored a policy of state-led family participation.

It's not just the cement road, but in Chang'an City, the cheap bookstore is the most concerned by everyone, and the price of books here is several times higher than that of other bookstores. And the number is so large that it is the best in the Tang Dynasty.

Because Li Er directly typeset and printed all the books treasured in the palace. Those great families may have more rare books, unique books, but the books in the palace are not far behind.

The advent of printing technology has allowed Datang to have more readers, most of whom are scholars from poor families, and the cost of reading is much higher than that of the family, and the original borrowing and copying of books is required to go to the family.

This is also the reason why most of the officials in the Tang Dynasty are not from the family, but they are all on the side of the family. When they were studying, they had to give in to the family, and this was the most fundamental reason.

Because each family has a large collection of books, these books are their most precious things, and all scholars who want to read need to turn to them to make their mark.

The scholars who came out in this way will become officials in the future, and they belong to their faction. Moreover, in the past, if scholars wanted to read, they also needed to borrow books, not to mention, the cost of copying books alone was incredible. Pen, ink, paper, and inkstone all require a lot of money.

If you are talented and learned, but your family is poor, then you can only rely on the family's relief, so as to further your relationship with the family, and it is even more difficult to maintain your independence and become a member of the family.

During this period of time, Li Er has let the people who will be the supervisor overcome the problems of printing, such as the most difficult ink, ordinary ink can not guarantee the quality of printing, after the research of the skilled craftsmen who will be the supervisor, the qualified ink has finally been obtained, so that the Datang cheap bookstore appeared.

This is great news for the poor people of the world, who are no longer confused by the high price of books, and do not worry about finding books on the market that they can read. The Maison's monopoly was shaken at this time.

Not only that, but there are more changes that make Datang continue to move in an unknown direction. For example, the symbols of broken sentences recorded in the books of cheap bookstores, and so on.

In short, the biggest change in Datang is Chang'an City, because it is the source of all new things, and it belongs to the first sequence in the entire change of Datang. And these are still on the surface, and there are many changes hidden underground.

In the Tang Imperial Palace, the north of the Yeting Palace is Taicang, and the area close to the Linzhao Palace to the east of Taicang has a three-entry courtyard. It was completely sealed, and even the troops on duty here were wearing iron armor and holding horse lances.

This is Li Er's personal guard, Xuanjiawei, there was originally a passage between Linzhao Hall and Taicang, but it was also closed at this time, but it completely became a forbidden area. There is no Li Er's edict here, and no one is allowed to enter or leave.

Because this is the place where Li Er researches gunpowder, this is the area where Li Er arranged for his confidant Duan Zhixuan to personally take charge, working during the day, and at sunset, there is a complete ban on smoking and fire, and the surrounding courtyard walls are filled with siege equipment in the army.

The gunpowder was put out little by little, and then packed into ceramic jars, iron jars, and then sealed, leaving a long lead.

After all these things were allocated, they had to be registered, and all the gunpowder used and how much was weighed every day, and if there was any inaccuracy, then all the people in the courtyard had to be counted.

In short, Li Er's control of gunpowder was completely to the point of strict defense and fire and water and fire. In the entire courtyard, except for himself, only Duan Zhixuan can have the right to enter and exit directly, and the rest of the people have to go through a strict search if they want to enter or come out.

The configuration of gunpowder in the palace is really a very unsafe situation, but Li Er is reluctant to put this thing in a farther area, because he is always not at ease because it is far away.

Of course, he has not used these gunpowder weapons in the Northern Expedition this time, because he was researching the best recipe before, and when the army was marching north, there was not much inventory.

However, now that the army has been on the expedition for several months, and there is already an objective stock of gunpowder in Taicang, Li Er is ready to transport a batch to the north.

Not only gunpowder, but there is another research that has also reached a critical moment, but this research is far away from Chang'an, which is the opposite of the treatment of gunpowder.

Because this research is a plague sore, and it will be a terrifying existence of a plague if you don't pay attention to it, Li Er directly sent the research team to the depths of the Qinling Mountains, and Sun Simiao, who had been summoned to Beijing before, presided over the research.

At this time, there was good news that the convicts who had been inoculated with cowpox had not been infected with sores after coming into contact with the patients, and that a larger scale of testing was needed.

This good news made Li Er very happy, and the entire second year of Zhenguan could be regarded as the most comfortable time he had in these years. It's just that he is still a little worried about the war situation on the grassland, because the grassland people actually set up a situation so that Datang was almost planted in it.

This is what Li Er is most worried about, he doesn't think that there is only one Zhao Deyan who is sowing discord in it.