Media playback is unsupported on your device Media caption Martin Patience reports on the largest human migration on the planet

Countries across Asia are beginning Lunar New Year celebrations to welcome in the year of the sheep.

In China, hundreds of millions of people are travelling home in what is considered the world's biggest annual human migration.

State media says about three billion passenger trips will be made by plane, train and car over the 40-day period.

It is a public holiday in many places with ethnic Chinese populations such as Taiwan, Singapore and Malaysia.

Media playback is unsupported on your device Media caption Confusion abounds as to whether the coming year is dedicated to the sheep, ram, or goat

The festival is known as Tet in Vietnam and Seollal in South Korea, and is traditionally a time to be with family.

In a speech at the Great Hall of the People on Tuesday, Chinese President Xi Jinping extended Lunar New Year greetings to Chinese people everywhere.

Media playback is unsupported on your device Media caption A fireworks display has marked the start of the Lunar New Year in Beijing

This year the government is urging people not to set off firecrackers, amid rocketing pollution levels in cities.

Image copyright Reuters Image caption Also known as the Spring Festival in China, celebrations kick off with a large meal, known as the reunion dinner, on New Year's Eve on Wednesday. Families make great efforts to be together for this, with some people travelling for days.

Image copyright Getty Images Image caption China's transport ministry has predicted that the travel rush will see 295 million railway trips

Image copyright Reuters Image caption Many will bring food, clothes and other belongings back home for the festival

Celebrations in Shanghai, and in many other Chinese cities, have been toned down this year after a stampede at New Year event in January left 36 people dead.

On Wednesday, Hong Kong leader CY Leung also gave his holiday message, describing the last year as full of conflicts and urging citizens to "be like sheep".

Late last year, a pro-democracy movement brought crowds onto the streets, blockading parts of the city and deeply dividing public opinion.

Various groups came together to demand the right to pick their own leader, without Beijing selecting which candidates can stand for elections.

"Sheep are widely seen to be mild and gentle animals living peacefully in groups," Mr Leung said.

Image copyright Getty Images Image caption The 15th Century Temple of Heaven in Beijing sees an annual re-enactment of colourful ancient ceremonies to welcome in the new year.

Image copyright AFP Image caption A woman poses with a sheep display in Hong Kong, which like many cities has put up colourful decorations for the season. The year of the sheep can also be called the year of the goat, because the Chinese character is the same.

Image copyright Getty Images Image caption In Seoul, these South Korean women found some more lively sheep to pose with at a cafe.

Image copyright EPA Image caption This ethnic Chinese man in Bangkok, Thailand, was burning paper money as a traditional new year offering to his ancestors.

Image copyright AFP Image caption Many people in the region will be looking forward to exchanging red packets - hong bao - containing "lucky" cash.

Image copyright AFP Image caption Traditional lion dancers took to the floor of the Philippine stock exchange in Manila, collecting lucky red envelopes of cash.

Image copyright Reuters Image caption These lion dancers were performing in front of the Royal Palace in Phnom Penh, Cambodia.