No Mountains Span Tajikistan to China with Those Slope Orientations

There are no mountains whose western slopes are in Tajikistan and eastern slopes in China.

Geography

• Tajikistan lies west of China (specifically, west of China's Xinjiang Uygur Autonomous Region).
• The border runs along the Pamir Mountains—the "Roof of the World."
• Major border ranges: Trans-Alay Range (north), Wakhan Range (south), Muzkol Range, Sarykol Range (on Chinese side).

Slope Orientation

Because Tajikistan is west of China:

• Mountains on the border have western slopes in Tajikistan and eastern slopes in China—this is the normal orientation for any border range.
• The question's phrasing implies a single range spanning both countries with that orientation, which describes the entire Pamir border zone, not a specific named range.

Key Border Peaks

• Ismoil Somoni Peak (7,495 m) – highest in Tajikistan, near border.
• Kongur Tagh (7,649 m) – highest in Pamirs, on Chinese side (Kashgar).
• Muztagh Ata (7,546 m) – Chinese side, "Father of Ice Mountains."

No single named range has "western slopes in Tajikistan and eastern slopes in China" as a defining feature—it's true of the entire border cordillera.