1.8.1 Position of predeterminers

Rule: Predeterminers precede determiners before the head noun.

Examples of errors:

(1) Your both farms were isolated, weren't they?
(2) Rangon and his both friends went to a restaurant.
(3) They suppose that one-of the both women lost it.

The predeterminers (all, both, half) are so called because they usually precede determiners (the, a, this, my, etc.). The only exception to this is when all or both (but not half) follow the head noun or be in sentences like

Your farms both were isolated.
Your farms were both isolated.

Some American speakers, may also say the both of us instead of both of us, but this is considered substandard. Both is also semantically unacceptable in (3), since singling out one of a pair (one of) is incompatible with the meaning of both as dual (i.e. 'one as well as the other'). This would only be possible in a sentence like

One of both pairs of women lost it

where the meaning is 'one person from each of the two pairs'.

For examples of the usage of both by German learners, click here.