President Vladimir V. Putin of Russia is scheduled to meet with President Trump in Alaska this week to discuss the war in Ukraine. If they talk about Ukrainian land concessions as part of peace negotiations, as Mr. Trump has suggested, they will be doing so on land that Russia sold to the United States in 1867.

That won’t be the only historical irony. Russia was moved to sell Alaska partly because of a war in Crimea, a peninsula that the Russian Empire annexed in 1783 under Catherine the Great. Crimea became part of an independent Ukraine in 1991, and Russia seized it in 2014 in a preview of its full-scale invasion of Ukraine in 2022.

As ironies go, “it doesn’t get much better than that on a grand historical scale,” said Pierce Bateman, a historian at the University of Alaska Anchorage, referring to the location of the Trump-Putin summit.

The $7.2 million purchase of Alaska now looks like a very good deal for the United States. Though it made sense for the Russian Empire at the time, some Russian nationalists see the sale as a historic blunder.

Here’s what to know about the forces and people that shaped it, and why its legacy matters:

Russia acquired Alaska during an era of colonial expansion.

Russian explorers reached present-day Alaska in the 18th century by crossing a narrow strait separating Asia and North America. The strait was named after Vitus Bering, the Danish-born mariner sent abroad by Czar Peter the Great in the 1720s to claim new Russian territory.

Professor Bateman said there was a “wild west” feeling in the territory as early Russian explorers rushed to harvest sea otter furs — a prized commodity in China at the time — in and around the Aleutian Islands.

There was also brutality against Indigenous people, including abductions of the children of local leaders and the destruction of boats and hunting equipment, according to William L. Iggiagruk Hensley, a historian and former Democratic state senator in Alaska.

Alaska’s economic appeal for Russia faded over time.

In 1799, the Russian Empire chartered the Russian-American Company to streamline the fur trade and formalize Russian settlements in the territory that would become known as Alaska. “Russian America” would eventually stretch as far south as California.

But overharvesting was making the fur trade far less profitable. There were also tensions among Russian, British and American fur traders, partly because the limits of their territories and hunting grounds were not well defined. And Russia’s sparsely populated settlements and assets were poorly defended.

Geopolitics were a factor in the sale.

The challenges of holding Alaska were complicated by developments on other continents. One was trade: Russia increasingly wanted to focus on imperial expansion in its Far East.

Another was war. When Russia began fighting Britain, France and the Ottoman Empire in Crimea in 1853, Russian officials worried that British forces might try to invade the Russian Far East through North America, according to a 2016 book about the purchase of Alaska by the historian Lee Farrow. Even after that threat subsided, they continued to worry about the British presence in the Pacific.

They also wondered if “Russian America” would survive U.S. expansionism. By the 1850s, the United States had acquired California, annexed Texas and fought a war with Mexico. There was talk of “Manifest Destiny,” the idea that the United States was destined to expand across North America.

Russian officials, including the commander of its Pacific fleet, urged the ailing empire to offload Alaska while it could.

The deal made sense for both sides.

The diplomatic conditions for a sale were good, according to Dr. Farrow, a professor at Auburn University at Montgomery. Trade between Russia and the United States was blossoming, and both were increasingly distrustful of Britain, America’s former colonial master.

In March 1867, Secretary of State William Henry Seward opened the negotiations by offering $5 million for the territory to Eduard Stoeckl, the Russian minister to the United States.

Two weeks later, they agreed on $7.2 million, or less than two cents an acre. A treaty was signed in Seward’s office at 4 a.m. after an all-night negotiating session, and later approved by Congress and Czar Alexander II.

The deal led to some tension and scandal: The U.S. government was late to pay Russia, and there were accusations that American politicians and journalists had taken cuts of the payment as bribes. Some critics did not see the strategic advantage of adding a frozen territory more than twice the size of France, and called the purchase “Seward’s folly.”

But the resistance was largely driven by a minority of American newspapers, according to a 2019 study by the historian Michael A. Hill. Many Americans were excited about Alaska’s rumored natural resources, he wrote.

Some Russians have seller’s remorse.

Alaska turned out to have plenty of resources, including gold, timber and petroleum, and the purchase was increasingly seen as a good deal for the United States. Alaska became the 49th state in 1959.

In Russia, there was some relief after the deal. But by the Soviet era, it was seen as an embarrassment, said Julia Davis, the founder of the Russian Media Monitor, a project that tracks Kremlin propaganda.

Mr. Putin, who often talks about the need to restore Russian power, equivocated in 2014 when asked if Russia planned to annex Alaska. But a sense of seller’s remorse over the lost territory seems to be a feature of his rule, Ms. Davis said, and calls to take Alaska back have grown louder as relations with the United States have worsened.

“Alaska is ours” billboards popped up in Russia after the invasion of Ukraine in 2022, and the message was amplified by some politicians and television pundits.

In that sense, holding a Trump-Putin summit in Alaska is a victory for hard-right Russian nationalists.

“Across the board, it’s considered a major win,” Ms. Davis said.