Opium was introduced in China by the British.
De Tocqueville wrote is masterwork, "Democracy in America" after touring the country. He found that the nation was strong, but that racial disparities and voting discrimination made the democracy very flawed
The Persian king Darius first attacked Greece in 490 BC, but was defeated at the Battle of Marathon by a mainly Athenian force. ... The Athenian Acropolis was destroyed by the Persians, but the Athenian response was to build the beautiful buildings whose ruins we can still see today.
Countries trade with each other when, on their own, they do not have the resources, or capacity to satisfy their own needs and wants. By developing and exploiting their domestic scarce resources, countries can produce a surplus, and trade this for the resources they need.