During his presidency, Donald Trump's reported attempt to buy Greenland was widely ridiculed. However, his proposal wasn't as outlandish as you might think.

Many countries, particularly the US, have purchased sovereign territory over the years. In fact, in 1916, when America bought the Caribbean islands that we now know as the US Virgin Islands from Denmark, the US actually agreed that Greenland would fall within the Kingdom of Denmark as part of the deal.

Read on for 31 astonishing examples of nations buying all or parts of other nations throughout history. All dollar amounts in US dollars.