This policy setting allows you to require that the device password be at least a specified length. The Require Password policy ...

"This policy setting allows you to require that the device password be at least a specified length. The Require Password policy setting MUST be enabled for this policy setting to take effect.  If you enable this policy setting, then you can set the required minimum password length. If the user already had a password set, and it does not meet the new password length requirement, the user is asked to create a new password once this policy setting is set on the device. The minimum length can be set to any integer between 1 and 40.  If you disable this policy setting, no minimum length will be enforced and the default values are used. The default for Simple PIN is 4 digits, and for Strong Alphanumeric is 7 characters.   If you do not configure this policy setting, then existing password-related settings on the device remain in effect."