They have trade partners such as china and other islands
a breach in the contract -C.-court of appeals case
B: Naval warships covered with iron.
Imperialism is the intention of one country to rule over another country: for example Great Britain wanted to gain control over India - this is an example of imperialism.
For this land is definitely needed : without a land, there is no "other" land to take over.
I would say that the other necessary aspect is people: the ruling country will need some local population to rule the country, if not only to translate and help them communicate with the local population.
