At 6 pm, Yang Tian dragged his tired body back to the five story building.

Xiaoqinglong\'s spirit is surprisingly good. He opens his eyes wide and lies on Yang Tian\'s shoulder. He looks at Yang Tian with two plastic bags full of fresh meat from the trunk of the car.

In the bag, Yang Tian met a "Silver Pig" in the process of practicing knife technique. After cutting it, he cut some meat from his body.

Unfortunately, the Silver Pig didn\'t even reach the level. Of course, there was no animal nucleus in his head.

Back to the five story building, Yang Tian endured fatigue, cut the silver pig meat into small pieces, sprinkled with seasoning, roasted it on the fire with a fine iron stick string, and threw it to Xiaoqinglong.

Yang Tian doesn\'t know why the little guy likes barbecue so much. After eating it for two days, Yang Tian is a little tired. He thinks it\'s not as delicious as the meat in the beef can, but little Qinglong doesn\'t get tired of it.

Yang Tian takes a bath and tells Xiaoqinglong to be smart at night. He lies in bed with a knife and closes his eyes. He falls asleep in a few minutes.

I don\'t know how long later, Yang Tian heard the sound of "squeaking" and a roaring sound. He opened his eyes fiercely.

Yang Tian saw the little green dragon lying on the head of the bed and listened to the roar of horses running outside. He was very surprised. He immediately turned over from the bed and sat up. He quickly put on his clothes in the dark, came to the window with a knife, and carefully opened the curtain to look out.

It was a moonlit night. The situation outside looked clear. Under the bright moonlight, Yang Tian saw a large number of strange animals. They ran in groups through the streets outside towards Tianxiong city.

Animal tide!

These two words suddenly appeared in Yang Tian\'s head.

The outbreak of YS virus has been nearly a hundred years. The safety zone established by human beings will experience an animal tide every once in a while for decades.

Animal tide is a large number of strange animals attacking cities established by human beings in groups. Generally, there will be a small animal tide every three or four years, and a large animal tide every ten years.

Looking at all kinds of strange animals running through the street outside, Yang Tian felt his scalp numb. So many strange animals, even senior martial arts, may be drowned by this herd soon!

The cause of animal tide has long been known by humans.

The high-level animals among the exotic animals are as smart as people. They take humans as their strong enemies. In addition, the breeding speed of exotic animals is too fast. Every few years, there will be a "surplus of animals". In order to keep their territory in order, these high-level animals will drive a large number of low-level animals to launch suicide attacks on the cities built by humans.

This can not only reduce the number of low-level animals, but also consume human resources. It\'s like killing two birds with one arrow.

The outbreak speed of animal tide is very fast. The warning time for human beings is generally only a few hours. After the animal leader gives orders in the territory, a large number of animals will gather around in just one or two hours, and then move towards the human city!

After taking a look outside, Yang Tian carefully put down the curtains, held the knife, sat under the window and waited quietly. Now is not the time to go out. If surrounded by a large number of strange animals, there is only a dead end.

Barren hill city is only more than 50 kilometers away from Tianxiong city. When the herd arrives, the people in the warning area are estimated to have retreated into the city. The people in the city will start a round of war with exotic animals relying on the 100 meter high wall.

The reason why humans can find the animal tide and make preparations in advance is that there are satellites in the sky to monitor the animals at all times. The animals are scattered and difficult to observe, but once they gather, they are a large moving red on the satellite infrared map.

Every animal tide is an opportunity for martial artists to make huge profits and show themselves!

Human cities have been built very strong. When the herds attack the bottom of the city, the high-energy weapons above the city wall can deal a devastating blow to the herds.

When the herd is scattered, it will be a feast for the warriors! The warriors in the city will take the opportunity to rush out of the city to hunt animals and harvest a large number of animal cores.

The low-level animals running outside have not found Yang Tian yet. It is estimated that they are urged by the high-level animals. There is only one idea in their mind, that is, rush to the city in front.

Yang Tian held the knife, slightly closed his eyes and waited quietly. As soon as the herd passed, it was time for him to go out!

Waiting quietly, I felt that time passed very slowly. Yang Tian raised his wrist from time to time to see the time.

When Yang Tian was awakened by little Qinglong, it was more than three o\'clock in the morning. Half an hour later, the herd passed through the barren hill city.

At this time, Yang Tian still didn\'t take action.

……

Under the moonlight, the tents outside Tianxiong city had long disappeared. Under the 100 meter high wall, there was all domestic garbage. People living in the warning area had long been put into the wall to avoid the animal tide.

The population of a city is limited. For the benefit of the majority, only a few people can be sacrificed. There are such people outside almost every city. Most of them are wandering people after the outbreak of YS virus. Finally, they gather when they find the city.

Some of them were people who broke the rules of the city and were driven out of the city. Others, like Yang Tian, have the qualification to live in the city, but are not satisfied with the status quo. They go out of the city to experience and want to be strong.

For decades, people living outside the city have had offspring, and the population has increased a lot, which is not much different from the population in the city.

If so many people revolt in another era, they can occupy the whole city. However, in this era of monsters and warriors ruling the world, these people are only vulnerable groups in human beings. They have no foundation for rebellion and can only survive by relying on the struggle of the city.

People living outside the city are also a resource for people in the city. Most of the food in the city is provided by people outside the city, but the city provides them with medicine and weapons.

After the outbreak of the animal tide, the city\'s managers allowed people outside the city to escape behind the city wall, but they were absolutely not allowed to live in the city for a long time to avoid undermining the order in the city.

You know, people inside and outside the city have completely different ideas about the system. Public security in the city is good, and most people have the awareness of abiding by discipline and law. And people living outside the city, their idea is to respect the strong. For some quarrels, they can draw a knife to kill.

When Yang Tian woke up more than ten minutes later, the herd approached Tianxiong city.

This is a small animal tide, which broke out in the east of Tianxiong city. It can be estimated from satellite images that there are about millions of exotic animals. Before these monsters approached the wall, the weapons on the wall opened fire.

The wheezing sound of laser guns, the explosion sound of conventional rapid fire artillery shells, the click sound of high-power machine gun firing, and the Zizi sound after electric mine explosion are intertwined, breaking the tranquility of the night.

Laser, electric light and fire light lit up the sky. Even if it was tens of kilometers away, these lights all passed through the window and flickered on Yang Tian\'s face.

Under Tianxiong City, a herd of low-level monsters braved the rain of guns and bullets to attack the city wall. They were very fast. After losing a few companions, they ran to the bottom of the city.

The wall does not have a 90 degree angle with the ground and inclines outward. If foreign animals want to attack the wall, they must climb with their own claws.

Even above the city wall, there are flat firing large caliber machine guns and high-voltage power grids.

The attack of the herd began at more than three o\'clock in the morning and lasted until seven o\'clock in the morning. It was not over yet, which surprised the managers of Tianxiong city.

From the experience of the outbreak of animal tide for decades, the attack of the herd will generally only support more than an hour. After a small number of exotic animals are killed, the herd will disperse.

Now, it has lasted more than three hours, and low-level monsters are still attacking desperately. Many monsters have climbed up the wall.

Although all these monsters were electrocuted by high-voltage power grids or killed by large-diameter machine guns. But if the strange animals continue to attack like this, they are likely to attack the city and cause damage to the residents in the city.