They refused to bend to the will of Congress, so Mormons set off for Mexico by horse and wagon, their bags packed with dried fruit and baked goods, their belief in polygamy unshakable.

It was 1885. That year, Mark Twain published "Adventures of Huckleberry Finn." A French ship delivered the Statue of Liberty to New York City. A skyscraper went up in Chicago. And the U.S. government had just outlawed polygamy, plural marriage that critics equated with slavery.

To avoid arrest, hundreds, then thousands, of Mormons fled to land purchased by The Church of Jesus Christ of Latter-day Saints in the Chihuahua desert, the site where at least nine people - three women and six children - would die in an ambush of a fundamentalist Mormon family Monday, Nov. 4 .

Polygamy was eventually renounced by the church. But for Mormons, the colonies established in Mexico represent an important chapter in church history - an event, as historian Carmon Hardy described it, that "constituted the last great effort of Mormonism to retain its peculiar nineteenth-century integrity by physical flight from an unfriendly environment."

One of the families that made the trek to Mexico was the family of Gaskell Romney, grandfather of Sen. Mitt Romney, R-Utah. Gaskell Romney's only wife gave birth there to Mitt's father George Romney, who, like his son, ran for president of the United States. (Mitt's great-great-grandfather Miles Park Romney had multiple wives.)

Getting to Mexico was arduous.

Without reliable maps, the families traveling by wagon relied on notes and drawings pinned to trees by settlers traveling the same routes before them. They came under constant surveillance by hostile indigenous peoples. Arriving at the Mexican border, customs officials charged them hundreds of dollars in duties.

In Mexico, life for the Romneys and other Mormons was both backbreaking and mystical, as Washington Post reporter Nick Miroff recounted in 2011 during Mitt's campaign for president. The family, he wrote:

". . . lived out of wagon boxes and helped chisel irrigation canals along the sides of the valley to plant apple orchards, which soon became the most productive in Chihuahua. When the river ran dry, the colonists prayed for water, according to family lore, and the 1887 Sonora earthquake struck soon after, rupturing an aquifer upriver, as if by providence. Water has flowed reliably through the valley ever since."

About 4,000 Mormons ultimately made the journey to two provinces - Chihuahua and Sonora - where they settled in eight communities, according to "The Trek South: How the Mormons Went to Mexico," a 1969 academic paper in the Southwestern Historical Quarterly.

But their time there was somewhat truncated.

For one thing, the church began phasing out polygamy, all but ending such weddings by 1904, according to the academic journal article. That stopped more settlers from coming, depriving the communities of new resources.

And then, during the Mexican Revolution in 1912, Mormon migrants became targets of violent attacks by rebel leader Inez Salazar. Almost all of the Mormons fled back to the United States, with large numbers of them settling in Texas.

But some Mormons, including Romney's relatives, stayed and still live in the region today. They are separate from the fundamentalists, who still immigrate to the region to practice polygamy, including the LeBarons, the family targeted in this week's attack.

This article was written by Michael S. Rosenwald, a reporter for The Washington Post.