In Ryan Coogler’s Sinners — set in 1932 Clarksdale, birthplace of the blues — music that alleviates pain can also invite spirits. The supernatural horror flick is anchored by blues melodies, with Coogler exploring the historical and cultural significance of an oral musical tradition born in the Mississippi Delta amid pain and suffering.To get the sound of the film right, Coogler roped in Oscar-winning composer Ludwig Göransson, who toured Memphis — home of the blues, rock ‘n’ roll and the famed Beale Street, where blues music thrived — to get the twangy guitars and the mournful sound in place.What is blues music?Blues is an oral musical tradition born in the aftermath of slavery, in the fields of the American South. It was survival music — sung in the cotton fields and rail yards as a work song, sometimes as a holler and sometimes an expression of longing and pain, all of it gradually evolving into what we now recognise as the blues: a 12-bar approach marked by repetition, improvisation, and the doleful blend of guitars and storytelling.While its chord progressions and simple structures are usually sparse, its emotional depth has continued to resonate. “You don’t sing to feel better. You sing ’cause that’s a way of understanding life,” Ma Rainey, one of the earliest professional blues singers, would say.History and evolution of blues musicWhile blues as a form is relatively well-documented 20th century onwards, the story is older and quite fragmented, mainly because blues was considered an inferior form of music and thus attracted less academic interest in terms of documentation.The roots of blues music trace back to the Transatlantic Slave Trade among Africa, Europe and America between the 16th and 19th centuries. The slaves on the ships carried the trauma of uprooting and dehumanisation, but also carried rhythm, language, spiritual traditions, and some musical instruments.All of the factors, when combined, resulted in a musical expression that gave them a sense of identity and community when they sang together, especially when engaged in mechanical and tedious jobs such as on cotton plantations.Story continues below this adGradually, as slave labour gave way to the sharecropping system in the late 19th and early 20th century, the group singing style declined, giving rise to solo singing. Group singing continued in the prisons of the American south, where black prisoners worked while chained together.The holler songs were also more personal, sad songs, with an impression of Arabic music due to Islam’s long presence in West Africa. Many of these were documented by musicologist and teacher John Lomax and later by his son and ethnomusicologist Alan Lomax.Why did the blues grow in the Mississippi Delta?Many geographical, social, and cultural factors contributed to the growth of the blues in the Mississippi Delta. After slavery was abolished, the red fertile soil of the region drew in thousands of Black labourers. For sharecroppers, things were only marginally better than slaves. Blues came from sweat and sorrow, from the isolation, the violence during this era.By the 1920s, musical figures like Ma Rainey, gospel legend Blind Lemon Jefferson, and supremely popular Bessie Smith had begun recording on phonograph records. They were followed by Robert Johnson, Muddy Waters and Howlin’ Wolf — names now etched into American musical history.Story continues below this adThe blues would later grow and evolve in cities like Chicago and Memphis.The Robert Johnson story that gave rise to the popular ‘the crossroads’Sinners also explores the mystery of the blues by interweaving musical folklore and the stories of the ‘devil’ associated with the genre, inspired by the mythical lore of blues legend Robert Johnson, who once, down and out as a musician, supposedly sold his soul to the ‘devil’ in exchange for supernatural musical powers.His music eventually inspired greats like Eric Clapton, the Rolling Stones and Muddy Waters.Story continues below this adCalled ‘the crossroads’ literally and metaphorically, and a significant motif in blues music, the place where the deal is said to have happened now exists in Clarksdale at the intersection of two highways . Three giant cobalt blue guitars adorn it, and the place remains a popular tourist spot. This engagement with the legacy of the blues is also why Sinners has found much attention.How did the blues become the heart of modern American music?“The blues is the root, everything else is the fruit,” Willie Dixon, a famed Chicago bluesman, said once.The blues music travelled with the Great Migration in the mid-20th century, where millions of black people seeking better economic opportunities and respite from racial discrimination migrated to the Northern and Midwestern states, setting up in places like Detroit, Chicago and Memphis. This is where the blues evolved and amalgamated with many other musical forms.Story continues below this adJazz musicians like Louis Armstrong incorporated a lot of blues elements into their music. Early country, R&B, soul and even rock music drew heavily from it. Rock musicians made it quicker and louder. The Rolling Stones even took their name from a Muddy Waters song, while blues tunes and phraseology have been instrumental in Bob Dylan’s music.Global popstar Beyonce has also credited the blues as a significant influence that shaped her sound and identity.