Netflix’s Black Summer has become one of the genre’s most intriguing TV shows, taking influence from the likes of Zack Snyder’s Dawn of the Dead to create a more action-packed, intense and rabid spin on zombies. However, there’s been some question as to whether it’s a prequel to Syfy’s Z Nation, with many fans finding the relationship between the two unclear.

In Z Nation, people were turned into zombies thanks to the NZ1 virus, and that series took place three years after the outbreak. Black Summer, though, occurs mere months after, showing how an unnamed zombie virus spread like wildfire, evolving to become airborne. Like in The Walking Dead, everyone is infected, and once they die, they turn into a zombie.

Karl Schaefer, who served as the showrunner for Z Nation, created Black Summer with Z Nation executive producer John Hyams. Thus there’s already the foundation for connective tissue. This backs up how the series initially was sold to the media as well: as a prequel. Notably, the term “Black Summer” has been mentioned in Z Nation’s Season 1, Episode 2, “Fracking Zombies.” There, survivors revealed how right after the outbreak, in the summer that followed, there was extreme drought and resources were really scarce. This led to many people dying, which increased the population of the undead, thus this summer where nature turned on mankind too snowballed into the predicament today.

Black Summer doesn’t lean into this, though, instead focusing on winter in Season 2 and the idea of refugees and xenophobia in a dog-eat-dog world. This feels a lot more personal, self-contained and emotive, playing as a political statement. It’s a totally different tone compared to Z Nation’s slapstick comedy and action, which was all about scrambling to stay alive in the militaristic America and find a cure.

Interestingly, Black Summer does throw a passing nod to one of these militaristic groups when stragglers in Season 1 at an abandoned cafe mention it’s getting very sinister in Philadelphia with people turning on each other. This alludes to the start of the cannibals — Philadelphia Cannibal Survivor Group — who evolved years later.

However, not all of those involved in the shows believes that there’s a connection. Jamie King, who plays Black Summer lead Rose, claims there’s no common ground. However, she didn’t see Z Nation so she wouldn’t know about any references. Thus, she might just be trying to get her series to stand on its own feet. But the evidence is there that says otherwise.

Still, while both may be years apart with no common cast members, there’s creative and spiritual overlap thanks to these passing references and the common production team behind the shows. So ultimately, that undeniable Philly reference seals the deal, making pretty clear that Black Summer is a prequel to Z Nation.