One of the coolest moments from Marvel’s Avengers: Infinity War take place in Wakanda, when the warrior-kings of the region, including Chadwick Boseman’s T’Challa and Winston Duke’s M’Baku, start a series of war chants. The moment captured in the film was unscripted, according to Infinity War directors the Joe and Anthony Russo.

The brothers commented on the chants during their Blu-ray commentary for Avengers: Infinity War, saying the improvised scene was “incredibly cool.”

“We di not know–because we had not seen Black Panther because they were still making Black Panther–about their war chants,” said Joe Russo. “And they just started doing it.”

The brothers said Duke led the chants, which Boseman answers with his own chants.

“And after watching Winston doing it in the opening of the sequence, it led to the responding war cry that T’Challa leads,” said Joe Russo. “A year ahead of time, we had no idea ‘Wakanda forever!’ was going to be amazing.”

Indeed, the Wakanda scenes in Infinity War have become fan favorites, so watching what happens to many of the Wakandans post-Thanos’ snap is heartbreaking. Since Infinity War and Black Panther were being filmed at the same time, no one realized that the latter film would become one of the best and most beloved films from the Marvel franchise, leading me to wonder if Marvel underestimated T’Challa’s worth to the franchise and to fans. However, we should see a resolution come in 2019 when the second half of Infinity War is released.

Infinity War is currently available for digital download and will be available on Blu-ray Aug. 14.

Russo Bros.