burial chambers were decorated (from the burial of Seti I onwards) with what became formalised as the Book of the Heavens, which again describes the sun's journey through the twelve hours of night. Again from Seti I's time, the Litany of Re, a lengthy hymn to the sun god began to appear. Tomb equipment Each burial was provided with equipment that would enable a comfortable existence in the afterlife. Also present in the tombs were items used to perform magic rituals, such as shabtis and divine figurines. Some of the items may have been used by the king during his lifetime (Tutankhamun's sandals for example), and some were specially constructed for the burial. Tomb numbering The modern abbreviation "KV" stands for "Kings' Valley". In 1827, Wilkinson painted KV numbers over the entrances to the 21 tombs that lay open in the East Valley at that time, beginning at the valley entrance and moving southward, and labeled four tombs in the West Valley as WV1 through WV4. The tombs in the West Valley were later incorporated into the East Valley numbering system as WV22 through WV25, and tombs that have been opened since Wilkinson's time have been added to the list. The numbers range from KV1 (Rameses VII) to KV64 (discovered in 2012). Since the early 19th century AD, antiquarians and archaeologists have cleared and recorded tombs, with a total of 61 sepulchers being known by the start of the 20th century. KV5 was only rediscovered in the 1990s after being dismissed as unimportant by previous investigators.[58] Some of the tombs are unoccupied, others remain unidentifiable as regards to their owners, and still others are merely pits used for storage.[59] Most of the open tombs in the Valley of the Kings are located in the East Valley, and this is where most of the tourist facilities are located. Eighteenth Dynasty The Eighteenth Dynasty tombs within the valley vary quite a bit in decoration, style, and location. It seems that at first there was no fixed plan. The tomb of Hatshepsut has a unique shape, twisting and turning down over 200 metres from the entrance, so that the burial chamber is 97 metres below the surface. The tombs gradually became more regular and formalised, and those of Thutmose III and Thutmose IV, KV34 and KV43, are good examples of Eighteenth Dynasty tombs, both with their bent axis, and simple decoration. Perhaps the