The soil of Kathmandu valley is fertile because all the fertile soil, gravel is deposited in the valley which is brought by the several rivers around the hills which flow into the valley.
Lichchhavi period is known as the Golden age because in LIchchhavi period there was the tremendous progress in the field of art, culture and philosophy.
Mallas did the progress in all around the development of the country. They did progress in the field of trade, art, architecture, etc. The buildings, palaces, temples, ponds, statues, etc were made in the period of Mallas.
There are various dynasties that ruled over Kathmandu valley. Some of them are Kirant dynasty, Mahispal dynasty, Gopal dynasty and Malla dynasty. The first dynasty that ruled over Kathmandu valley is Gopal dynasty which ruled about 521 years. Then after Mahispal dynasty came into the power. Mahispal dynasty ruled over the valley for about 161 years. After Mahispal dynasty, Kirant dynasty ruled over the valley. They ruled for about 1118 years in the valley which was the highest rule over Kathmandu valley in the history of Nepal. After defeating Kirant, Lichchhavi came into the power and after them, Mallas came into the power. After defeating Mallas, King Prithvi Narayan Shah unified the whole nation which is called Nepal.