(FORTUNE Magazine) – Anadarko, Oklahoma, isn't exactly the sort of place you'd expect to find an offshore bank. For starters, this small Western town is landlocked in the middle of farm and cattle country--in other words, decidedly onshore. It's got a population of 6,600 and a median household income of $21,000, and you'd be hard pressed to find much of anything to do there, save hunting, horseback riding, and the occasional meat-pie bake-off. So what makes the town's First Lenape Nation Bank an offshore bank, exactly? The answer is tribal sovereignty. First Lenape is owned by the Delaware tribe of western Oklahoma, a sovereign Indian nation whose independence from U.S. state and federal authority has been federally recognized since 1934. So in return for getting their land stolen, the Delawares, who were originally from their namesake state and were exiled to Oklahoma, get to operate a bank that can guarantee Swiss-style banking secrecy to both tribal members and nonmembers. That means numbered accounts, full nondisclosure of account information, no compliance with snooping law enforcement, protection from civil court judgments (wage garnishments and the like), and no reporting of interest to the IRS or of cash deposits over $10,000 to the Treasury Department.

Whether the Delawares can really do all this remains to be seen. Since there's no U.S. tribal law relating specifically to banking and no tribe has ever attempted to build a little Cayman Island in the middle of Indian country, this pugnacious bank is entering virgin territory. Nothing expressly says the Delawares can't do it, so they simply went ahead and built an addition onto the bingo hall in their tribal headquarters complex and set up shop. Such gunslinging enterprise is, after all, how the West was won. But before you dismiss the whole notion as an absurdity, remember that the idea that a bunch of Indians could ignore federal and state gambling laws and build casinos in the middle of states like, say, Connecticut, seemed pretty preposterous not so long ago.

Chartered by tribal government in December as the central bank of the Delawares of western Oklahoma, First Lenape began accepting trial depositors in early March and was soon fielding more phone calls and letters than it could handle. CEO A.C. Yardley, a former attorney with a background in tribal law, says that correspondent relationships with other Oklahoma banks were being nurtured and that $5 million in investment capital had been committed by a collection of wealthy individual investors. A Website was even constructed to advertise the bank's services. Encouraged by what he calls an "overwhelming" response, Lawrence Snake, chief of the tribe, started envisioning a day when capturing even a tiny piece of the booming offshore banking market--which the Santa Barbara-based Offshore Outlook magazine estimates at $3.5 trillion in bank deposits and trust accounts--might mean economic self-sufficiency for the tribe. The Delawares are dependent on an annual $500,000 government subsidy and suffer from 45% unemployment. Snake dreamed of using First Lenape capital to run an agriculture business on currently unused tribal land, to buy an insurance company, and to build a string of highway gas stations from Oklahoma to New Jersey tracing the historical trail of the tribe's forced migration.

That was all before the regulators got wind of the novel scheme. Alarmed by what is, after all, a brassy attempt to circumvent the huge regulatory edifice of state and national banking law, Oklahoma's state banking commissioner's office issued an alert in late March to Oklahoma banks and the general public advising "extreme caution in any transaction involving [First Lenape]." The Office of the Comptroller of the Currency, the federal government agency that charters and regulates national banks, followed several days later with its own warning to some 3,000 member banks. These warning bells quickly scared off potential banking partners, and First Lenape stopped taking new deposits. The bank is now in talks with the Treasury Department and the Department of Tribal Justice, a 2 1/2-year-old division of the Department of Justice, both of which, unsurprisingly, have a few "concerns" about First Lenape's aims. They're the same concerns that propel the IRS and the Treasury Department to seek agreements with every island-nation that declares itself an offshore haven--namely, tax evasion and money laundering. First Lenape insists it wants only legitimate capital, but dirty money hardly comes with a label attached, and the three-member tribal board that was set up to review and enforce anticrime compliance procedures doesn't exactly constitute the FBI (though these days that may be a good thing).

The government's concerns are certainly worthy. Too bad they have little power to act on them. Broadly written tribal-sovereignty laws that mandate equal, government-to-government negotiations with tribes put Native Americans in the unique position of being the only Americans who can basically tell the government to go to hell. Sure, authorities can attempt to wield influence over tribal government or modify tribal law through congressional action, but given the sad history of relations between the government and Native Americans, bullying Indians just doesn't look good. The one piece of leverage the regulatory authorities do have is that First Lenape needs their blessing to establish relationships with other banks.

The message in all this for anyone contemplating a wire transfer to Anadarko is, stay tuned (one way to do this is via the bank's Website, firstlenapenationbank.com). The fate of First Lenape will have interesting implications for the scope of tribal autonomy, not to mention the possibility of booming nightlife in Anadarko. One thing's for certain: If First Lenape succeeds, expect offshore fever to spread much in the way Indian-owned casino gambling has.

--Melanie Warner