Muslim historian and geographer Al Masudi (871-957CE) wrote in his book "The Meadows of Gold and the Quarries of Jewels" that during the rule of the Muslim Caliph of Spain Abdullah ibn Muhammad (888-912CE), a Muslim navigator Ibn Aswad crossed the Atlantic in 889 CE, reached an unknown territory (ard majhoola) and returned with fabulous treasures.
In Al Masudi's map of the world there is a large area in "the ocean of darkness and fog" (Atlantic ocean) which he referred to as the "Unknown Territory" (identified today as South America).
Muslims in the Americas and the Caribbean
From Before Columbus To the Present
Dr. Abdullah Hakim Quick
Ta-Ha Publishers Ltd, London, 1998.
Refer to wesite http://www.cambridgemuslims.info/DidYouKnow/
Medieval Islamic Coins found near Cambridge, MA
Evidence of Muslim presence in the Americas before Columbus
Medieval Islamic coins of North Africa from a buried hoard found in 1787, during road-building excavations between Cambridge and Malden, Massachusetts, USA. (Coins A and B)
From Saga America, Barry Fell, 1980, Published by Times books, New York, pages 26-27, 30.
We have, in fact, a long history of recovering ancient coins from American soil -- coins that, for some unaccountable reason, we have persistently contrived to ignore. Take, for example, the events that occurred some two centuries ago on a stretch of highway only a few minutes' drive from Massachusetts (USA).
The year was 1787, and the Reverend Thaddeus Mason Harris was making his way along the Cambridge-Malden road (now known as Route 16), probably turning over in his mind the prospects of the young Republic, whose very Constitution was that year being hammered out by the Congress summoned for that purpose. As he rounded a bend, he saw before him a cluster of people gathered about some unusual object. As he afterwards recorded in a letter to John Quincy Adams, he learned that some workmen had been engaged in widening a section of the road when a pickaxe had struck a horizontal flat slab of stone buried beneath the surface. When the slab was cleared and prized up, it was found to serve as a protective cover of a concealed cache of ancient coins, of which "two quarts" now lay exposed to view, hundreds of small square pieces of base metal (a copper-silver alloy) each bearing unknown signs stamped on the faces. The finders concluded that they were worthless, and passers-by, including Harris himself, were invited to take away handfuls. Hundreds of coins were thus dispersed."
Of all the people who carried off samples of these curiosities, Harris alone took steps to place the matter on record. After fruitless attempts to identify the inscriptions (actually Kufic, an ancient form of Arabic) and research in Harvard Library to no result, he had illustrations drawn and these, together with the account he sent to John Quincy Adams, were published by the American Academy of Arts and Science, in Boston. And there the matter rested for nearly two hundred years, until James Whittall, of the Early Sites Research Society, chanced upon the old report written by Harris and took steps to notify me and the American Numismatic Society."
Coin C: Smarkand coin struck in 903 CE and found at Gulland, Denmark.
Islamic coins have been found in hoards of hundreds in both America and Scandinavia. Some of the Islamic coins found in America may have been brought by Norsemen, as thousands of such coins of the ninth to the eleventh centuries are found in the soil of Scandinavia.
Coins A and B: Medieval Islamic coins of North Africa from a buried hoard found in 1787, during road-building excavations between Cambridge and Malden, Massachusetts.
Coin C:, coin of Smarkand struck in 903 AD and found at Gulland, Denmark. The central inscription reads: 'There is no god but Allah alone, and no partner for him.' The marginal inscription reads, 'In the name of Allah was coined this drachma [dirhem] in Samarqand.'
From Saga America, Barry Fell, 1980, Published by Times books, New York, pages 26-27, 30
This articel from http://www.cambridgemuslims.info/DidYouKnow/CambridgeMA/