Ten Ton Hammer Writes:
All Death Knights begin the game in the Eastern Plaguelands in an instanced area that isn't connected to the rest of Azeroth. They train to become a Death Knight by gaining their sword, their abilities, and their rank through a series of quests before they're sent out into the world… slightly reformed.
The main NEW area of the Death Knight starting area is called "Archerus: The Ebon Hold". This is a floating necropolis where all of the new Death Knights begin their journey. Specifically, if we were to name a location, it would be at the top where the Lich King stands. The other "new" area in the instanced portion of Eastern Plaguelands is called the "Scarlet Enclave" which contains the outdoor area where all of the combat happens.