That's not good. Isn't that a big danger to civs?
All the CZ-1 to CZ-4 Series rockets were launched in Jiuquan, Taiyaun and Xichang. From the beginning each launch would meet this problem that the booster and first stage would drop inland.
It's all because of the cold war.
At the very first days when China started its Areospace plans, China was afraid of the attack from the sea by US Navy. The first launch centers Jiuquan was located in the north west provinces of Gansu in 1950s, so that USN attack aircrafts cannot touch it.
Then the second launch center Taiyuan was located in Shanxi province in 1967, hundreds of kilometers away from the coast. This time the threats from USSR was seriously considered.
Later when the China-USSR relation dropped to a freezing point, China decided to build a third base at Xichang, located in the South west province Sichuan, about 2800 km away from the Chian-Russian border. The construction started in 1969 when border conflicts broke out between China and USSR, but finished late in 1982 when China-USSR relation already slowly warmed up again.
So all the first three launch centers are located inland, mostly determined by military safety consideration. The launching balistics was carefully calculated so that no large cities was under the rocket's orbit. But China is a dense populated country, so it's almost imposible to avoid all the residential area.
Since 1960s, there were totally over 300 launches from these three launch center. In 1996 there was one launch accident causing mass civilian loss, six people killed and tens injured, due to early stage mechanical failure and the rocket hit the nearby residential area. But there were almost no casuality cases reported due to the normal descent of the boosters or first stages of other rockets.
Finally when China started to carry out its ambitious space exploration program in 2010s, a new low-lattitude costal launch center was built. And this time defence security is not the key factor to the choosing of location. Wenchang, located in the island province of Hainan, at about 19.5°N was selected. The first stage and boosters of rockets will fall into the west pacific, and the huge sections of the CZ-5 and future CZ-9 can be tranported by ships, never get limited by the railroad vehicles and tunnels again.
In 2021 a new launch center was planned in Xiangshan, Ningbo City, Zhejiang province, at about 29°N, which will be the main launch center for all commercial new rockets.