This is a classic case of "chain immigration"--the number of foreign-born Indians in the Dulles Corridor has grown ninefold since 1980. But it is also a case of chain entrepreneurship: Many of these immigrants were drawn to Northern Virginia out of a desire to start companies of their own.

To understand the rise of this community of Indian entrepreneurs, you have to understand what drew them. A good place to start is 1983. The company that would become AOL was born one block south of the newly completed Dulles Toll Road. The fledgling AOL came to represent the democratization of the Internet and other technologies made possible--or affordable, at least--by government investment. The toll road carries traffic between the nation's capital and the information-technology consultants who can manage data and help the federal government move from mainframes to personal computers.

Beneath the concrete lies another traffic conduit: fiber-optic lines made for moving information rather than vehicles. Half of all U.S. Internet traffic flows through the Dulles Corridor. Twenty years ago, this was exurbs. Today, it's the Silicon Valley of the East, which has become a magnet for immigrants from India.

If the Dulles Toll Road is the artery that conveys technology to the government, it is social networks--trade organizations, mentors, and networking--that help infuse the entrepreneurial fresh blood.

One such catalyst is Sudhakar Shenoy. The founder and CEO of a high-tech consulting firm and a past chairman of the Northern Virginia Tech Council, Shenoy sees his greatest impact--like many Indian entrepreneurs--as a mentor. He teaches a course he calls "From Geeks to Gazillionaires" at nearby George Mason University that helps aspiring M.B.A.s and engineers polish their business pitches. Students are divided into teams, and the one with the winning business plan receives the semester salaries of Shenoy and his co-teachers as a cash prize. He also cofounded the Washington chapter of the Indus Entrepreneurs, a global network of mostly Indian business owners, investors, and mentors. "When it comes to helping entrepreneurs," he said, "Indians are always there." If Indians are drawn to Northern Virginia for the high-tech opportunities and stay for the excellent public schools, Shenoy explained, they succeed because of the network of support from other Indians.

Perhaps no one embodies this culture of giving back more than Dolly Oberoi, the president-elect of the Indus Entrepreneurs. Her story parallels Shenoy's. Oberoi immigrated to the United States "with 200 bucks and a backpack" to obtain a master's degree, and then landed a job with a Virginia consultancy. She, too, started her own technology firm, C2 Technologies; its annual revenue has grown to $50 million. And nowadays, she embraces mentorship as a second career.