Eurasia was the colloquial name of the landmass on Earth that was made up of the continents of Europe and Asia.
By the 23rd century the term was used to collectively represent the unity of both continents. (TOS: "Dagger of the Mind")
Hikaru Sulu noted that the rocket launched from McKinley Rocket Base was projected by the computer to impact somewhere in the heart of the Euro-Asian continent. (TOS: "Assignment: Earth")