"The word ‘empire’ comes from the Latin word imperium; for which the closest modern English equivalent would perhaps be ‘sovereignty’, or simply ‘rule’". The greatest distinction of an empire is through the amount of land that a nation has conquered and expanded. Political power grew from conquering land, however cultural and economic aspects flourished through sea and trade routes. A distinction about empires is "that although political empires were built mostly by expansion overland, economic and cultural influences spread at least as much by sea". Some of the main aspects of trade that went overseas consisted of animals and plant products. European empires in Asia and Africa "have come to be seen as the classic forms of imperialism: and indeed most books on the subject confine themselves to the European seaborne empires". European expansion caused the world to be divided by how developed and developing nation are portrayed through the world systems theory. The two main regions are the core and the periphery. The core consists of high areas of income and profit; the periphery is on the opposing side of the spectrum consisting of areas of low income and profit. These critical theories of Geo-politics have led to increased discussion of the meaning and impact of imperialism on the modern post-colonial world. The Russian leader Lenin suggested that "imperialism was the highest form of capitalism, claiming that imperialism developed after colonialism, and was distinguished from colonialism by monopoly capitalism". This idea from Lenin stresses how important new political world order has become in our modern era. Geopolitics now focuses on states becoming major economic players in the market; some states today are viewed as empires due to their political and economic authority over other nations.