When is Asia not called Asia?
Countries located in the Middle East region that are also on the Asian continent are part of Asia but people simply refer to the region as the Middle East and exclude these countries when making reference to Asia. The vast majority of Russia is in Asia, but even when you are in the Asian portion of Russia, normally you wouldn't say you're in Asia. Asian countries like the Philippines and Indonesia are not physically on the Asian continent just like Britain is not on the European continent, are sometimes referred to as Pacific Islands rather than Asia. And then there is the Eurasian continent, Europe and Asia combined is actually one single continent, in this sense you would just say Eurasia to mean both Europe as well as Asia, such as "China is located in Eurasia."