CLOTHING
Essential apparel for your riding holiday
A merino wool t-shirt
A long-sleeved t-shirt or shirt
A fleece and/or a down jacket
A rain jacket
Two pairs of underwear
A sports bra
A bra
A pair of leggings
Short hiking trousers
Overtrousers
Two pairs of socks, one low pair and one long pair in wool
A pair of gloves
A hat
A pair of hiking socks
A pair of sandals or flip flops
A pair of waterproof shoes
Bonus: canvas shoes and trousers for a look that fits in anywhere you visit.
CAMPING EQUIPMENT
A tent
A canvas sheet
A sleeping bag
A sleeping sheet
A sleeping mat
A pillow
An emergency foil blanket
COOKING
A portable stove
A set of meals
Folding utensils
A good quality knife
A sponge
A lighter
Salt, pepper and seasonings
A water filter
TOILETRY BAG
A swimming costume
A microfibre towel
Soap/Shower Gel
A toilet roll sealed in a ziplock bag
Toothbrush + toothpaste
Nail clippers
A tick removal tool
A first aid set and some medicines
TOOLS
A spare inner tube
A set of tyre levers
A puncture repair kit
A pump
A multitool
A pair of pliers for a quick-release chain
A chain tool
Two pairs of quick-releases for a chain
An adjustable wrench
A spoke wrench
Several spokes with spare heads
A cassette removal tool
Wire cutters
A derailleur cable
A brake cable
A set of brake pads
Bike Oil
A cloth
String
Strong adhesive
Several nylon clamps nylon (rilsan)
Gloves to keep your hands clean
MISCELLANEOUS
A neckwarmer
A cap or hat
A helmet
Good quality sunglasses
A flexible lock with a code (avoiding the need for keys)
A good book/eReader
A notebook (to make sure you don't forget anything)
An MP3 player with lots of battery
A headlamp

This is not the ULTIMATE list, you should adapt it to your needs and your destination. But it's a great place to start!