Vassals had to serve lords because the vassals promised to serve a lord in exchange for land.
The vassals required to give their king land. They could also give the king food, water and a sword.
10
vassals
vassals
Vassals could receive more land from the lord and if they were rich enough, vassals could become a lord to other vassals. Feudalism could become confusing.
Investiture
Homage
Lords granted lands to vassals because they had a lot of land and needed men to fight in their armies. They also couldn't manage their land alone. As a solution, a lord would give land to vassals in exchange for the vassals agreeing to fight in his army. The vassals would have peasants and serfs work their land.
Yes it does become a vassal of the java kingdom.
To control his men in battle and to help manage his estates at home. These men needed to be loyal to him, especially in battle.
through a ceremony called the "Kiss and Peace" ceremony.
The main reason men become sterile is the cause of a low sperm count. One could also choose to become sterile and have a vasectomy so as to not have any more children.
Vassals were loyal to the person(s) above them. Therefore a king may have a vassal who may have other vassals loyal to him. A vassal has power over his serfs, or his vassals. Also the vassals have power over the peasents.
Vassals had to serve lords because the vassals promised to serve a lord in exchange for land.
The plural of vassal is vassals. As in "our vassals have sent us gifts of silk".
In many cases, vassals did have their own vassals, in a process called subinfeudation. There is a link below, but it does not give as much information as I would have liked to find.