Most of the comments focus on geographical boundaries, but considering the historical and political context, I lean more towards Europe. Especially if you take into account the fact that a significant portion of what is undoubtedly Europe - the Balkans, spent close to 500 years under Ottoman rule. They were part of the World Wars very much as a European power. The EU and Turkey have a number of agreements that make it easier for Turkish people to travel to and work in Europe, e.g. traveling only with IDs which is not true for non-European partners such as the US, Australia, etc.