Short answers, pulled from the story.
The taka replaced the Islamic gold dinar in Bengal in the year 1338. This shift occurred when the Moroccan traveler Ibn Battuta observed the local silver coin displacing the standard currency of the Muslim world in the bustling markets of Bengal.
The basic unit of the silver tanka weighed exactly one tola or 11.2 grams and was composed of 96 rattis of silver. This standard was established by Sultan Shams al-Din Iltutmish of the Delhi Sultanate in the 13th century to reflect the dual heritage of Muslim settlers and native Indian populations.
Muhammad bin Tughluq attempted to change the value of the tanka by minting it in copper and brass while claiming its value was backed by gold and silver reserves in the imperial treasury. This radical monetary experiment modeled after the paper money systems of the Mongols in China and Persia collapsed into chaos and led to the downfall of the Tughluq dynasty.
The Tibetan government began minting its own tangka currency in the year 1763. By 1792, the Qing dynasty established mints in the region, and these Sino-Tibetan tangka coins carried Chinese language inscriptions to bridge the gap between the Himalayan kingdoms and the Chinese empire.
The modern Bangladeshi taka was officially introduced in the year 1972 by the Bangladesh Bank. This new currency replaced the Pakistani rupee at par following the end of the Bangladesh Liberation War and is produced by Bangladesh's Security Printing Corporation.