if your alliance, travel through from ironforge into dun morgh too loch modan and then you enter badlands.
if your horde, go from orgrimmar too grom gol then travel through stranglethorn vale. into duskwood then head towards redridge and then go from redridge too burning steppes (50+ zone) then too searing gorge (45-50) and then you enter badlands.
that or the lower level route that takes longer from undercity all the way down too loch modan.
or get level 44 and enter the zone through the travel quest which is the easiest way.(as an horde)
The Badlands is an arid and desolate region in Khaz Modan accessed via the Searing Gorge to the west and Loch Modan to the north. Only the hardiest of creatures can survive in the arid wastes, such as feral coyotes, cougars and buzzards. The black dragonflight have a pronounced presence in the area, mainly in the Lethlor Ravine and, later, in the Dustbowl. Scattered across the Badlands are camps of the Dustbelcher ogres.
Despite its position between Stormwind and Dun Morogh, the Badlands have traditionally been Horde territory, though the Alliance have recently established the encampment of Dragon's Mouth in the western part of the region. To the north of Dragon's Mouth lies the Horde stronghold of New Kargath, built after its predecessor was buried by an avalanche during the Cataclysm. In the east is the goblin town of Fuselight and its sister port town, Fuselight-by-the-Sea, both controlled by the neutral Steamwheedle Cartel. In the west, a massive, charred ravine called the Scar of the Worldbreaker was formed when Deathwing passed through the area.
In the northeast, near the border with Loch Modan, lie the ruins of a titan-forged fortress known as Uldaman, home to titan-forged earthen, savage troggs, and much information about the origins of the dwarven race, while the smaller Tomb of the Watchers has recently been unearthed in the center of the region. As a result, the Alliance-affiliated Explorers' League, the dwarven Dark Iron clan and the blood elven Reliquary are fighting for control over the ruins and any titan artifacts that may lie within.
Players can access the zone by using a rocket from Light's Hope Chapel in the Eastern Plaguelands that goes to the goblin port, Fuselight-by-the-Sea, with the quest Fuselight, Ho!.
It is also accessible on foot by a mountain pas from the Searing Gorge, or alternatively, from Loch Modan, by a ramp that leads down the chasm between the two zones and another one back up.
The Badlands is a high desert valley, bone dry and hot. The Searing Gorge is to the west, while the lush Loch Modan is located in the mountains to the north. Searing winds blow the heat around but do nothing to cool this sweltering land. The harsh environment allows only the heartiest plants — cacti and shrub brush — to survive. You can bring plenty of water, but it still might not be enough. It is advised for you to read up on your desert survival skills before coming here, travel at night and sleep during the day.
The Badlands are rocky and flat. Mountains to the north block cool air and moisture from Loch Modan. Canyons surround the Badlands, and they are rife with lions and vicious humanoids. Only the hardiest plants and animals survive — withered trees, cacti, scorpions and bobcats. The landscape also hides rock elementals. The smaller ones are easier to kill. Run from the bigger ones unless you want to see what you look like as a pasty smear on the ground.
Teleporter in Booty Bay
The second quickest route (assuming you don't already have flight points in Arathi or Hillsbrad) makes use of a teleporter in Booty Bay, accessible via a short quest chain that starts in Orgrimmar. This path goes through two low-level Alliance regions, so is more risky on PvP servers, but fairly easy on PvE servers. If you are a level high enough to survive in the Badlands, you should not have much problem. Do the following:
From Sovik in Orgrimmar, get the Scooty quest [NOTE: due to the devastating Cataclysm, this quest is no longer available]. You may need to accept Rig Wars from Nogg first, but you do not need to complete it.
Get to Booty Bay (see here).
Find Scooty (south of the tavern) and turn in the quest. Scooty will issue you another quest, but all you need to do is stand there for a minute to complete it. Turn that in to get the item that allows you to use the transporter.
Step on the teleporter
You materialize inside Gnomeregan, quite close to the entrance. Most of what is around you will be hostile, but are only around level 24.
Move into the entrance elevator (to the southeast). You'll probably need to kill the Leper Gnomes guarding the room. Take the elevator and exit Gnomeregan.
Follow the roads in Dun Morogh, moving all the way to the east. Avoid towns, and follow the signs to Loch Modan.
Go through the Southern Gate into Loch Modan. You'll need to either fight or avoid the guards. The road will lead down a long hill to a T intersection. Take a left.
Travel through Loch Modan to a gap in the center of the southern mountains, right below the tip of the lake. Avoid towns.
Go through this gap into the Badlands.
Once in the badlands, Kargath is in the most western part. Keeping an eye out for mobs, skirt the edge of the mountains.
A more traditional route overland route runs from the Undercity through five other regions. With care, this can be done by level 20+ characters, but the distance is quite long so a travel form or mount is recommended. Of course, if you have one of the flight points listed below already, fly there from the Undercity and then continue from there.
Take the Zeppelin to Undercity.
Travel along the road South past the Undercity to Silverpine Forest.
Continue along the road in Silverpine and grab the flight Path at the Sepulcher.
Travel south from the Sepulcher along the road and turn east towards Hillsbrad Foothills.
Grab the flight point at Tarren Mill, then continue east towards the Arathi Highlands.
Continue east on the road and grab the flight point at Hammerfall. Then head south towards the Wetlands.
There is no Horde flight path in the Wetlands. Continue south on the road towards Dun Algaz.
Dun Algaz is a series of three tunnels between Wetlands and Loch Modan. The third and highest tunnel has a roaming 30's level guard inside the tunnel. There are more guards stationed at the tunnel exit into Loch Modan. To pass through the tunnel without fighting the roaming guard, position yourself to the right of the entrance tunnel up on the hillside. Wait for the roaming guard to exit the tunnel, then run quickly into the tunnel. You will be attacked on exiting the tunnel into Loch Modan. Have whatever defensive measures you have ready. Run as far out of the tunnel as you can. If you die in Loch Modan you will arrive at the Spirit Healer just north of Thelsamar. Slip into the woods and continue south to the Badlands if you opt not to return for your corpse.
If you successfully pass through Dun Algaz, keep heading south in Loch Modan. Avoid the Alliance town Thelsamar. Once you are safely south of Thelsamar, head east towards the Loch. Travel along the shore until you hit the southern most point and head south. Although it is not visible on the map, there is a path leading through the scar at the south end of the map. Look for a discolored area to begin your decent.
Once in The Badlands head south, then west always travelling along the mountains on the edge of the map (watch out for the stealthed tigers here). Soon you will reach Kargath.
If you die in the Badlands before the halfway point to Kargath, you will appear at the Spirit Healer near Loch Modan. If you die past the halfway point to Kargath, You will appear at the Spirit Healer just south of Kargath. Move quickly in the Badlands.
From Grom'Gol Base Camp
An overland approach also exists from the south, but it is even longer and much more dangerous, heading through a couple level 50+ regions:
Take zeppelin to Grom'Gol Base Camp in Stranglethorn Vale.
Follow the roads north into Duskwood.
Follow the road all the way to the northeast, avoiding the town of Darkshire (unless you like that kind of trouble). If you want to get the flight path at Stonard, you can dodge Darkshire and head eastward into Deadwind Pass. Here continue directly east, following the road, as there are high-level mobs just right off it (not close enough to aggro when you're on the road, though). When you get into the Swamp of Sorrows, follow the road (which is guarded by some Horde-friendly orcs) until you pass by the crossroads past Splinterspear Junction and take the southern road. Follow this road eastward, passing by the road leading to the Blasted Lands, until you reach Stonard.
The north road out of Darkshire will take you into the Redridge Mountains.
Follow the road north, avoiding the village of Lakeshire, into the Burning Steppes.
Ride to the north of the Ruins of Thaurissan to Flame Crest in the Steppes and grab the flight path there, then travel west and enter Blackrock Mountain.
Follow the path through the mountain (no mobs along the path) into Searing Gorge
Follow the road to the northeast.
After passing by a dwarven dig site on the right, turn right through a pass (70,54) to the east and enter Badlands.