What did the ancient indus valley, huang, and nile civilization have in common

The thing that indus Valley, Huang, and Nile civilization have in common is :
They began in fertile river valleys

The land/area near the fertile river valleys are always good for planting various types of crops since it's near the water supply and really high in minerals. a Perfect spot to start a civilization

The most obvious commonality between the civilizations on the nile, indus valley and huang was the fact that they were started and began building their civilizations in fertile river valleys. There is also a good reason for this as the ancient fertile river valleys offered a good starting point for any civilization. 

North korea has been ruled by dictator since 1948