Vocalization markers indicating specific vowel sounds were introduced into the Arabic language by the end of the 9th century. The first Quranic manuscripts lacked these marks, therefore several recitations remain acceptable. The variation in readings of the text permitted by the nature of the defective vocalization led to an increase in the number of readings during the 10th century. The 10th-century Muslim scholar from Baghdad, Ibn Mujahid, is famous for establishing seven acceptable textual readings of the Quran. He studied various readings and their trustworthiness and chose seven 8th-century readers from the cities of Mecca, Medina, Kufa, Basra and Damascus. Ibn Mujahid did not explain why he chose seven readers, rather than six or ten, but this may be related to a prophetic tradition (Muhammad's saying) reporting that the Quran had been revealed in seven "ahruf" (meaning seven letters or modes). Today, the most popular readings are those transmitted by Hafs (d.796) and Warsh (d. 812) which are according to two of Ibn Mujahid's reciters, Aasim ibn Abi al-Najud (Kufa, d. 745) and Nafi' al-Madani (Medina, d. 785), respectively. The influential standard Quran of Cairo (1924) uses an elaborate system of modified vowel-signs and a set of additional symbols for minute details and is based on Asim's recitation, the 8th-century recitation of Kufa. This edition has become the standard for modern printings of the Quran.
The absence of which language feature made early Quranic recitation more diverse?
Vocalization markers

Another important factor was that during the Middle Ages a large proportion of the population would have been illiterate and so pictures on a sign were more useful than words as a means of identifying a public house. For this reason there was often no reason to write the establishment's name on the sign and inns opened without a formal written name, the name being derived later from the illustration on the pub's sign.
In what historical period was a large portion of the population illiterate?
the Middle Ages

Norfolk Island has 174 native plants; 51 of them are endemic. At least 18 of the endemic species are rare or threatened. The Norfolk Island palm (Rhopalostylis baueri) and the smooth tree-fern (Cyathea brownii), the tallest tree-fern in the world, are common in the Norfolk Island National Park but rare elsewhere on the island. Before European colonization, most of Norfolk Island was covered with subtropical rain forest, the canopy of which was made of Araucaria heterophylla (Norfolk Island pine) in exposed areas, and the palm Rhopalostylis baueri and tree ferns Cyathea brownii and C. australis in moister protected areas. The understory was thick with lianas and ferns covering the forest floor. Only one small tract (5 km2) of rainforest remains, which was declared as the Norfolk Island National Park in 1986.
How much of the rainforest remains in Norfolk Island today?
5 km2