I saw this interesting question on the website Quora, and I decided to answer the question myself. Here is my take.
There are some serious points when considering how China views Southeast Asia. Allow me to at least elaborate briefly each point.
One must understand that it is deep inside China’s view to see everything through a historical perspective. Historically of course, many parts of Southeast Asia is considered tributary, or vassal to the Chinese Empire. This view somewhat sticks until today, with an implicit, but can be felt, feeling of “superiority”. I remember Hillary Clinton writes this event in which during a conference, one China representative shouted, which roughly says, “All Southeast Asian countries are weak, China is powerful.”
Ain’t Going Bilateral
That also holds true if one considers the way China engages in diplomacy with Southeast Asian countries. Rarely will China engages with ASEAN as a whole, rather it will take matters bilaterally. Of course, observers may say that China’s acceptance to the Treaty of Amity and Cooperation begs to differ. Yet one must also consider one very specific issue: South China Sea. In dealing with this particular predicament, it is more likely for China to take matters to each disputant, e.g. Vietnam or the Philippines. It is a simple matter of dealing with a weaker power—collective bargaining in ASEAN means facing a stronger power (albeit remains somewhat lesser than China).
We’ll show you how to drive
There is also a wonderful quote I take from a book (Shambaugh 2013), quoting a Singaporean diplomat how he understands the way China see Southeast Asia: “China used to be content to sit in the back seat of the regional multilateral car and let ASEAN [the Association of Southeast Asian Nations] drive, but now they have moved to the passenger’s seat, taken the map out of the glove box, and are telling us how to drive! It is only a matter of time before they try and take over the steering wheel.”
China also realizes, nevertheless, that Southeast Asia is a huge market for China. About 500 million people live in this region, and most of the economies are sustained by consumerism. The ASEAN-China Free Trade Agreement for instance, created fear among the ASEAN member states, because they realize how China will flood Southeast Asia with its goods, produced cheaply, in which locally-produced goods find themselves impossible to compete.
And finally, China finds it important to pay attention to the huge number of Chinese diaspora in the region. Indonesia, Malaysia, and Singapore in particular, have a lot of Chinese descendants. The issue of Chinese diaspora in the region has been dominating China’s foreign politics in the region ever since the 1950s (e.g. how Zhou Enlai specifically negotiated an agreement on citizenship for Chinese descents with Indonesia in 1955).
So there you have it. In a sum, China still considers Southeast Asia to be its subordinate, a tributary region, albeit remains difficult for China to realize that the region will still be important for China in many years to come.