The phoenix tail is a traditional Chinese knotting sennit. It is the same as a simple crochet chain if drawing from two balls and alternating between them for each stitch.
To start, form a bight on the left and over that bight, tie a half hitch with the right hand side. Take a bight of the right hand cord through the left loop, then pull tight the left loop. Tip: pulling up on the open loop while pulling down on the closing loop can help keep the tension even. Then take a bight of the left hand cord through the right loop and pull tight the right loop. Continue to pull loops through from alternating sides until desired length. A clean finish would be to pull both loose ends through the last loop. Top right corner images show the finished pattern, front and back. With round cord, there is little difference. Tied with stacked ribbons, the phoenix tail is a common lei technique and also makes a lovely garland that I have seen recommended for weddings as decoration or for hand fasting cord.