problem with running multiple stepper motor together on the same time

Hi all,
I was trying to run my three stepper motor together but it is running one by one. My written code is as follows. Please let to know where am i doing the mistake. Thanks a lot.

#include <Stepper.h>
Stepper myStepper1(200, 2, 3, 4, 5);
Stepper myStepper2(200, 6, 7, 8, 9);
Stepper myStepper3(200, 10, 11, 12, 13);
void setup() {
  Serial.begin(9600);
}
void loop() {
  
    myStepper1.setSpeed(50);
    myStepper2.setSpeed(50);
    myStepper3.setSpeed(50);
    myStepper1.step(200);    
    myStepper2.step(200);    
    myStepper3.step(200);
}

The standard Stepper library is not intended for what you want. You would need to make each motor move one step at a time and manage the step-timing with your own code.

The run() or runSpeed() functions in the AccelStepper library can control several motors at the same time.

There is also the MultiStepper library if you need your motors to move in a coordinated way - for example all motors start and stop at the same time even though they do different numbers of steps - like in a CNC milling machine or a 3D printer.

...R Stepper Motor Basics Simple Stepper Code