Gareth Williams, curator of early medieval coinage at the British Museum in London, said the concentration of early medieval coins in Gotland is "remarkable."
"We've got more surviving late Anglo-Saxon coins from Gotland than we have from Britain, despite the fact it's not a very big island and quite a way away," he added.
The newfound hoard, buried some 1,300 feet (400 meters) from the site of an ancient Viking settlement, also includes highly unusual coins minted for Olof Skötkonung, a regional Swedish king, Carlsson said.
"He was the first king that minted coins in Sweden," he said.
"He obviously learned [coin-making] from England," he added. "Many of the coins are copies of English coins, most of all Ethelred coins."
Ethelred II was England's monarch from 978 to 1016. Also known as Ethelred the Unready due to his lack of reliable counsel, he paid massive amounts of "tribute money" to the Vikings and is featured on Anglo-Saxon coins discovered in the garden cache.
Sihtric, the Viking ruler of Dublin, Ireland, was another king whose money turned up in the hoard.
Williams noted that a number of the Gotland coins show knife marks left by "pecking," a practice used to test whether they were genuine silver or counterfeits made of lead.
"A huge amount of coinage was making its way through there, more than the locals could ever possibly have had a use for," Williams added.
Many researchers believe these hoards functioned like safe deposit boxes: Viking cash deposits were hidden in the ground for safety until needed.
Other experts suggest that the caches had a religious significance and were saved up and buried by their owners for use in the afterlife.
(Read related story: "Vikings Filed Their Teeth, Skeleton Study Shows" [February 3, 2006].)
Huge Haul Found in England
The new find follows the discovery earlier this year of a major Viking hoard by amateur treasure hunters in northeast England.
That hoard was said by experts to be among the most important ever found in Britain.
Unearthed by amateurs using metal-detectors in a field near Harrogate, North Yorkshire (see map), the treasure included a rare gold armband, jewelery, and more than 600 coins collected from as far away as Afghanistan.
The hoard was stashed inside a decorated gilt silver vessel thought to have been looted from a monastery in France.
The treasure is dated to between 927 and 929, when the Anglo-Saxons regained control of northeast England from the Vikings.
A number of Viking hoards found in the region were buried around this period, according to Williams, of the British Museum.
"This was probably linked to the Anglo-Saxons pushing northwards," he said.
The Harrogate treasure likely belonged to an important Viking chieftain, he added.
Researchers can only speculate why he never retrieved it.
"He could have been killed in battle, forced to leave the region, or died of old age before he had a chance to recover it," Williams said.
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