The minaret was erected during the reign of Seljuq Sultan Sanjar (1118-1157) as part of an unidentified courtyard structure. It is located in Nad-i Ali, a field of ruins near the Iranian border that is now identified as ancient Zaranj, one of the medieval capitals of Sistan (a region in southwest Afghanistan and eastern Iran). Zaranj escaped Mongol raids led by Chingiz Khan in 1221, but was sacked by Timur's forces in 1383. Persia and Afghanistan disputed rights to the area from the sixteenth to the early twentieth centuries.
Built of baked bricks, the Nad-i Ali minaret was composed of a cylindrical shaft raised on a tapering octagonal base. An early twentieth century photograph by T. Ward (Royal Geographic Society) shows the base and a stub of its collapsed shaft; the base has also since collapsed. As shown in this rare photograph, the base was about ten meters high, and of a similar diameter. A wide semi-circular buttress was embedded at the center of each of base facet, creating an appearance of alternating rounded and pointed flanges. The minaret base was simply decorated with tall deep grooves in its brick revetment, composed of stacks of slits and crosses that terminated an 'upward pointing arrow' motif near the shaft.
Sources:
Knobloch, Edgar. The Architecture and Archaeology of Afghanistan, 29-33. Stroud, Gloucestershire, Charleston, SC: Tempus. 2002.
O'Kane, Bernard. "Saljuq Minarets: Some New Data." Annales Islamologiques XX (1984): 97-101.
Petersen, Andrew. "Afghanistan." Dictionary of Islamic Architecture. London and New York: Routledge, 1996. http://archnet.org/library/dictionary/entry.jsp?entry_id=DIA0003&mode=full [Accessed October 4, 2013]
Pinder-Wilson, Ralph. "Ghaznavid and Ghurid Minarets." Iran: Journal of the British Institute of Persian Studies 39 (2001): 155-186.