which data transmission medium will be suitable for distance more than 1 km

the data sensed by the sensor which is of few bytes is to be sent over distance more than 1km. Now the problem is its a hilly area, the source and destination doesn't have fair line of sight.

What is your data rate? What is your regulatory posture?

Radios like FRS or old CB can easily run over 1km, a
simple audio modulation (like pipe an antique 1200/2400
phone handset modem into the walkie-talkie, and back
the other way on the other end) could get you done.
But these bands are not for digital comms and over the
long haul you might get a visit or a ticket from the FCC
when somebody bitches about not being able to use
some channel. FRS has many more channels and in my
limited use, very low usage.

Data like temperature, or anything changing below 1kHz,
would be fine with this low bandwidth kind of link. You
want video, you're stuck with higher frequencies and
lower power (ISM bands being defined for more congested
areas like jabbering-equipment-filled offices).

Low frequency radio is not so line-of-sight sensitive.
Heck, AM radio you can hear cross-country (at the cost
of 100kW or so).

Given the (lack of) constraints in your specification, I suggest the simplest, most predictable and easiest technique to implement will be to copy the bytes onto a USB disk, and transport the disk to the receiver.

i have no idea abt data communication for long range. Now without any legal issue of UHF... can any RF module be used