<P> Names other than استانبول (İstanbul) had become obsolete in the Turkish language during the late Ottoman / early republican periods . However, Constantinople was still used when writing the city's name in Latin script . In 1928, the Turkish alphabet was changed from Arabic script to Latin script . After that, Turkey started to urge other countries to use Turkish names for Turkish cities, instead of other transliterations to Latin script that had been used in the Ottoman times . Letters or packages sent to "Constantinople" instead of "Istanbul" were no longer delivered by Turkey's PTT, which contributed to the eventual worldwide adoption of the new name . </P> <P> In English the name is usually written "Istanbul". In modern Turkish the name is written "İstanbul" (dotted i / İ and dotless ı / I being two distinct letters in the Turkish alphabet). </P> <P> Stamboul or Stambul is a variant form of İstanbul . Greek for' the town' . Like Istanbul itself, forms without the initial i - are attested from early on in the Middle Ages, first in Arabic sources of the 10th century and Armenian ones of the 12th . Some early sources also attest to an even shorter form Bulin, based on the Greek word Poli (n) alone without the preceding article . (This latter form lives on in modern Armenian .) The word - initial i - arose in the Turkish name as an epenthetic vowel to break up the St - consonant cluster, prohibited in Turkish phonotactics . </P> <P> Stamboul was used in Western languages as an equivalent of İstanbul, until the time it was replaced by the official new usage of the Turkish form in the 1930s . In the 19th and early 20th centuries, Western European and American sources often used Constantinople to refer to the metropolis as a whole, but Stamboul to refer to the central parts located on the historic peninsula, i.e. Byzantine - era Constantinople inside the walls . </P>

What was istanbul called in the middle ages