it made the invaders hard to get in because of the deserts, the cataracts.... and the river itself
It kept out invader's.
natural defense system that kept invaders out from trying to conquer
Nile River and the Sahara Desert were important natural barriers that kept the Egyptian people safe from invaders. I hope the information works for you.
The Himalayas and Gobi acted as natural barriers that kept invaders out of China.
The massive wall kept invaders at bay, and kept the interior of China safe for years. The Wall, combined with the Gobi Desert and mountain ranges on each end, served as a massive obstacle to invaders.
china kept out the mongols with the Great Wall
A wildlife sanctuary or natural reserve where animals are kept in their natural habitat for research purposes.
what natural occurrence kept the indus balley supplied with plenty of water
A nature reserve.
Roman History was divided into three parts: the monarchy, the republic, and the empire. It didn't have great defenses before the monarchy, but during the monarchy the defenses kept growing, and then Rome became so powerful that it barely had to worry about defending, because it conquered so much land.
Emperor of Qin Dynasty wanted to protect his people from the mongolian invaders to the north.
Frog eggs should be kept in natural water from a pond or rainwater. They should be kept in the same place and conditions they were laid in.