These historians study Brooklyn before it was cool. Way before.

Brooklyn is full of history, like the Lott House (pictured above). Much of it, however, hasn’t been studied by historians. Enter the “League of Flatlanders.”

At the last unofficial, semi-regular history salon at Café Hadar on Avenue N in Brooklyn, the discussion turned to the nearby Wyckoff-Bennett Homestead, a well-preserved historical house, and a one-time proposal to pave over a stone path with concrete.

“I like concrete,” says Malka Simon, a lecturer in architectural history and urban design at Brooklyn College, who specializes in industrial architecture.

Alyssa Loorya, an archeologist and founder of Chrysalis Archaeological Consultants, disagrees. Concrete doesn’t allow rain to seep into the ground.

“Well, not necessarily to put everywhere,” Simon admits, about the concrete.

They call themselves, jokingly, the “League of Flatlanders,” for the deep-South Brooklyn area they call home and in which they were born and raised.

They are devoted to investigating a history which they feel has been woefully understudied, even as the boundaries of hip Brooklyn edge ever closer to their turf.

This outer part of Brooklyn, particularly the areas around Marine Park and Midwood, has gotten little historical attention. Besides Coney Island, says Thomas Campanella, a professor of city and regional planning at Cornell University.

A good place to start the story of the region might be the Lott House — a Dutch Colonial farmhouse dating from 1719, owned by the same family until the new millennium, says Loorya, who helped to study and restore the site in the ’90s.

After 1989, the building was unoccupied and abandoned. Local residents took care of it as best as possible, hosing down the exterior before July 4 to keep firework sparks from igniting the wooden structure, says Loorya.

It wasn’t until the 2000s that archeologists, including Loorya, were able to investigate the site, now a historical landmark. They found a dwelling place for slaves and, later in the house’s history, evidence that it may have served as a stop on the Underground Railroad.

There’s no smoking gun, the group allows, but among the evidence are matching accounts from the family’s oral histories; a hidden nook within a closet; and the placement of the house just off Jamaica Bay, a quiet place to slip into the city and follow the road from the Lott House to Weeksville, a haven for freed slaves in Brooklyn that has recently gotten historical attention of its own.

Unlike Manhattan and downtown Brooklyn, the history of the area is marked by what didn’t happen.

Farmland until the 1920s, the area was quickly transformed into row houses by a wave of immigration and an economic boom. Designs for Marine Park, the neighborhood’s defining feature, once included a football stadium and expansive waterfront development. That plan was stopped by Robert Moses, New York’s king of highways and development. Nevertheless, Marine Park remained quiet and residential, fed by the cars for which the row houses and their driveways were built.

Many residents are interested in their local history, the group says — many pack the Lott House for holiday parties and the local civic association is supportive of restoration efforts — but there has been little academic work done about the area.

As New York City’s population grows and we plan future development, the history of these far-flung sections becomes even more important: How they became or remain livable, how they can be revitalized or preserved. And, of course, how they change.

The historians’ salon avidly discussed the new Starbucks on Flatbush Avenue, the impact of Mayor Bill de Blasio’s rezoning initiatives and the difficulty of obtaining a farmer’s market permit for Marine Park.

Perhaps attention is heading toward the deep-South part of the borough. Last summer, Campanella and Loorya were puttering around the ¾ acre property around the Lott House when they noticed a continual stream of bikers going down 35th Street, beach towels and folding chairs in tow. The two historians realized that 35th street was on the Google bike route from Williamsburg and other points north to the Rockaways.

They overheard riders stopping and saying, “Imagine having a big yard in Brooklyn.”

The two plan for next year to put up a sign, explaining the Lott House’s history, beyond its enticing open space.

This is amExpress, the conversation starter for New Yorkers.