The Registan contains three madrasahs (schools), the Ulugh Beg Madrasah (1417-1420), Tilya-Kori Madrasah (1646-1660) and the Sher-Dor Madrasah (1619-1636). The Tilya-Kori Madrasah was built in the mid-17th century by the Shaybanid Amir Yalangtush. The name Tilya-Kori means gilded or gold-covered, and the entire building is lavishly decorated with elaborate geometrical arabesques and sura from the Quran both outside and especially within. A magnificent turquoise dome rises over the left (western) side of the building, decorated inside with gilded Quranic inscriptions and delicate muqarnas hanging stalactite decorations. The interior of the madrasah comprises rooms for students with accompanying vestibules surrounding three-sides of a square courtyard, while a domed mosque occupies the fourth. The dome rises in four stages. A rectangular plinth forms the primary prayer hall and rises above the madrasa walls. Next, two terraced octagonal tiers rise to support a high cylindrical drum. The dome's monochrome blue color contrasts pleasingly with the drum's polychrome decoration formed by bands of Arabic calligraphy taken from the Quran.