"What is this, a stone?" Li Shimin looked at the things that Li Xiu offered, but asked with a puzzled face, and finally even knocked with his hand, confirming that this was a gray stone-like thing, and it looked very rough, but the specifications were boxy, as if they had been carved like this?

"Your Majesty is right to say it's stone, but I prefer to call it cement!" Li Xiu said with a smile at this time, what he dedicated to Li Shimin was the cement he had people burn during this time.

For this kind of building materials, Li Xiu has long wanted to come up, but in the past, Datang's productivity was low, and it was unrealistic to want to produce cement on a large scale, but now with his crossing, Datang has also undergone great changes, such as the use of coal, the promotion of hydraulic equipment, etc., which has greatly improved productivity, and now has the conditions for producing cement.

"Cement? What a strange name, but what's the use of this stone? Li Xiu picked up the palm-sized cement block at this time and weighed it, and then asked curiously again, the eldest grandson Wuji and Li Zhi next to him also looked at this inconspicuous "stone" with the same curiosity, even if Li Zhi was Li Xiu's student, but he still had never heard of the name of cement.

"Hehe, cement is not actually a stone, but a kind of lime, clay, gypsum mixed in a certain proportion, and then calcined with a fierce fire, and finally formed a powder, this powder is cement, and when used, as long as this powder is mixed with water, after a period of time, this powder will become this cement block like a stone." Li Xiu smiled again at this time.

Hearing Li Xiu's description, Li Shimin also felt very novel, but then he asked a little puzzled: "This cement is a little magical, but even so, what is its use?" ”

"Your Majesty, don't underestimate cement, it's too useful, because it's very hard when it is coagulated, almost like a stone, and it's not afraid of fire and water, so it's very suitable for building roads and cities......"

Li Xiu did not dedicate the cement to Li Shimin for no reason, but combined with the plan to annex the grassland, the cement was made, because if you want to control the grassland, you must send officials and garrisons, but there are no cities on the grassland, and there are no roads, and sometimes where it is passable, a heavy rain will turn into a swamp, which will bring great difficulties to the march.

But now with cement is different, Datang can use cement to build roads, and the hardened cement roads are not afraid of rain at all, in addition to building cities at the junction of the road, these cities can attract grassland people to settle, can also attract Han people to live, combined with the previous Han people to go to the grassland to reward fields and pastures policy, it is estimated that it will not be long before these cities can become prosperous places, plus the stationed officials and troops, naturally these places can be firmly controlled in the hands of the Tang Dynasty.

"Your Majesty, the city and the road are like the veins of our Datang, where they are cultivated, the rule of our Datang will extend to wherever it goes, of course, this is not an overnight effort, but even if it takes dozens of years, as long as the grassland can be completely annexed, the minister thinks it is worth it!" Li Xiu finally presented the cement to Li Shimin and his son again, and now he is not only sending cement, but millions of miles of rivers and mountains in the northern grassland.

Li Shimin finally understood the importance of cement at this time, and reached out excitedly to take the cement, with this thing, he could swallow the grassland into his stomach little by little, even if his generation could not complete it, he could also hand it over to Li Zhi to continue, and sooner or later a little grassland would become the territory of the Tang Dynasty.

"The horse is really a last resort, to lure, to coerce, and then to reduce the population on the grassland in various ways, to lure the people of the Central Plains to move to the grassland to live, as long as these strategies are implemented, sooner or later the northern grassland will be as stable as Guanzhong!" Eldest Sun Wuji also praised at this time, he is extremely good at summarizing, and in just a few sentences, he summarized Li Xiu's long Pingbei policy.

"Pheasant slave! You understand now, I'm afraid that the plan to annex the grassland can't be completed by relying on my father alone, and if you ascend the throne in the future, you will also implement Li Xiu's strategy! Li Shimin looked at Li Zhidao with serious eyes at this time.

"Father, rest assured, the sons and daughters will definitely keep today's events in mind!" Li Zhi also said very solemnly at this time, he followed Li Shimin to learn government affairs during this time, and also knew that the biggest border trouble in the Tang Dynasty was in the north, and the imperial court had to invest a lot of manpower, material and financial resources every year, if it could completely solve the threat of the northern grassland, then it would be worth the cost.

Seeing that Li Shimin and the eldest grandson Wuji agreed with his suggestion, Li Xiu couldn't help but show a happy expression, and then several of them had a detailed discussion of the entire plan, after all, even if Li Xiu has talent, no matter how long-term his vision is, but it is only his opinion, there will definitely be some omissions in some places, and now the wisdom of Li Shimin and the eldest grandson Wuji can supplement this plan more completely, and Li Zhi also put forward some of his own opinions from time to time, although some opinions are still immature, But sometimes the insights are very novel.

Such a huge plan, naturally it is impossible to rely on only a few Li Xiu and a few of them to complete, but it is necessary to mobilize the forces of all parties in the Tang Dynasty, and even if this matter is really implemented, I am afraid it is not easier than a big battle, so in the end, Li Shimin also summoned Fang Xuanling and other important ministers to the Liangyi Hall to discuss together, although some people feel that this plan is too huge and takes too long, but Li Shimin is determined to completely solve the border troubles in the north, so in the end he still got the consent of most people.

Speaking of which, the Tang Dynasty has also been operating the grassland over the years, especially the southern grassland close to the Tang Dynasty, most of the tribes are dependent on the Tang Dynasty, and even many tribes are yearning for the Tang Dynasty, so the resistance to making them completely Tang people is not very large.

As for the manufacture of cement, Li Shimin also decided to set up a cement workshop in the Taiyuan area, which is rich in coal and limestone, and is close to the northern grassland, and the fired cement can be easily transported to the grassland for road construction and city construction.

However, before the above plans are implemented, there is still one thing to pay attention to, that is, the defeated Bazhuo has fled back to Xue Yantuo, if Bazhuo does not die, Xue Yantuo is likely to have a resurgence.