Answer:
Mountain Ranges.
Explanation:
The natural boundary which shielded the Indus and Ganges Valleys from invaders to the north was mountain ranges. The world's tallest mountains that stood on the north of the Indua valley served as a guard to protect the Indus and Ganges valley from being invaded.
<u>Indus Valley is surrounded by the world's tallest mountain range of </u><u>the Hindu Kush, the Karakorum, and the Himalayas in the north.</u><u> Indus and Ganges valley form the most fertile landforms.</u>
Thus the correct answer is that the natural boundary of mountain ranges guarded Indus and Ganges Valley from being invaded.
A primary election. This is so the voter can choose a candidate from a political party, then to nominate them as the party's candidate
The Nile river no longer floods because of the Aswan dam built in the 1960s.
The correct answer is - India.
Columbus went on a mission to discover a sea route to India from the opposite side, or rather to move towards west so that he comes out on the eastern part of India. So when he discovered the islands in the Caribbean he had no idea that those islands are a part of a totally new world unknown to the Europeans (apart from the Vikings), and he thought that those islands must be islands situated east of India, so that is why he also gave the name Indians to the native populations he encountered.
The full name for our year is 2020 A.D., which stands for Anno Domini or "in the year of our Lord". This began at the birth of Christ. So, when we say we're in the year 2020, what we're really saying is that it's been 2020 years since the birth of Christ.