The second-generation Athlon, the Thunderbird, debuted in 2000. AMD released the Athlon XP the following year,[1] and the Athlon XP's immediate successor, the Athlon 64, was an AMD64-architecture microprocessor released in 2003.[16] After the 2007 launch of the Phenom processors, the Athlon name was also used for mid-range processors, positioned above brands such as Sempron.[17] The Athlon 64 X2 was released in 2005 as the first native dual-core desktop CPU designed by AMD,[18] and the Athlon X2 was a subsequent family based on the Athlon 64 X2.[19] Introduced in 2009, Athlon II was a dual-core family of Athlon chips.[20]