Some Black Lives Matter protesters have been riding horses to protests. Lil Nas X gave one of them props on Twitter.

• Lil Nas X, of "Old Town Road" fame, retweeted a video of a group of people riding on horses to a Houston Black Lives Matter protest on Tuesday.
• "The time has arrived," the rapper wrote.
• Protesters in at least four cities have ridden horses during protests to cheers from the crowd.
• Police officers have also been riding horses as a form of crowd control. One mounted officer in Houston trampled a woman, prompting Mayor Sylvester Turner to apologize to the woman directly.

On Tuesday, an estimated 60,000 people marched in downtown Houston, George Floyd's childhood home, to protest his killing by a police officer last week.

About two dozen of them showed up on horseback. The Nonstop Riders, an urban trail-riding club, joined the protest to cheers from the crowd.

One video, taken by the NBC News reporter Mike Hixenbaugh, was retweeted by Lil Nas X of "Old Town Road" fame.

"The time has arrived," he wrote.

While the Nonstop Riders captured the attention of Lil Nas X, they are not the first Black Lives Matter protesters on horseback.

Demonstrators in Chicago, Minnesota, and Oakland, California, have also adopted the tactic, which were common during the North Dakota Dakota Access Pipeline protests.

Brianna Noble rode her horse, Dapper Dan, to a protest in Oakland last Friday. When asked by The Guardian why she brought Dapper Dan, she said the idea came to her while she was watching the video of Floyd's last moments.

"I'm just another protester if I go down there alone, but no one can ignore a black woman sitting on top of a horse," Noble said.

Adam Hollingsworth, or the "Dreadhead Cowboy," was perhaps the first protester seen riding a horse at demonstrations over Floyd's death.

He made his first appearance in Minneapolis on May 27, joining in chants and, at one point, standing on his horse while flashing his middle finger at the police. Floyd died in Minneapolis on May 25.

Police forces across the country have also been riding horses to control crowds.

A video posted on Saturday showed a mounted police officer trampling a female protester, prompting the Houston Police Department to announce that it was investigating the incident and Mayor Sylvester Turner to apologize to the woman.